Transmit Control in Multicarrier Communications

ABSTRACT

Methods, apparatuses, and systems are described for wireless communications. Cells may be grouped into a plurality of cell groups. A wireless device may transmit or drop one or more of a plurality of signals.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/791,390, filed Feb. 14, 2020, which is a continuation of U.S. patentapplication Ser. No. 16/041,163, filed Jul. 20, 2018 (now U.S. Pat. No.10,681,701, issued Jun. 9, 2020), which is a continuation of U.S. patentapplication Ser. No. 15/715,092, filed Sep. 25, 2017 (now U.S. Pat. No.10,064,191, issued Aug. 28, 2018), which is a continuation of:

(1) U.S. patent application Ser. No. 14/622,969, filed Feb. 16, 2015(now U.S. Pat. No. 9,820,283, issued Nov. 14, 2017), which is acontinuation of U.S. patent application Ser. No. 13/862,430, filed Apr.14, 2013 (now U.S. Pat. No. 8,995,381, issued Mar. 31, 2015), whichclaims the benefit of U.S. Provisional Application No. 61/625,078, filedApr. 16, 2012, U.S. Provisional Application No. 61/661,361, filed Jun.19, 2012, and U.S. Provisional Application No. 61/700,869, filed Sep.13, 2012; and

(2) U.S. patent application Ser. No. 15/698,876, filed Sep. 8, 2017 (nowU.S. Pat. No. 10,523,389, issued Dec. 31, 2019), which is a continuationof:

(a) U.S. patent application Ser. No. 14/616,774, filed Feb. 9, 2015 (nowU.S. Pat. No. 9,763,203, issued Sep. 12, 2017), which is a continuationof U.S. patent application Ser. No. 13/862,420, filed Apr. 14, 2013 (nowU.S. Pat. No. 8,989,128, issued Mar. 24, 2015), which claims the benefitof U.S. Provisional Application No. 61/635,957, filed Apr. 20, 2012, andU.S. Provisional Application No. 61/654,900, filed Jun. 3, 2012,

(b) U.S. patent application Ser. No. 15/201,558, filed Jul. 4, 2016 (nowU.S. Pat. No. 9,867,137, issued Jan. 9, 2018), which is a continuationof U.S. patent application Ser. No. 14/960,391, filed Dec. 6, 2015 (nowU.S. Pat. No. 9,414,332, issued Aug. 9, 2016), which is a continuationof U.S. patent application Ser. No. 14/608,244, filed Jan. 29, 2015 (nowU.S. Pat. No. 9,210,665, issued Dec. 8, 2015), which is a continuationof U.S. patent application Ser. No. 13/862,424, filed Apr. 14, 2013 (nowU.S. Pat. No. 8,958,342, issued Feb. 17, 2015), which claims the benefitof U.S. Provisional Application No. 61/625,085, filed Apr. 17, 2012, andU.S. Provisional Application No. 61/661,329, filed Jun. 18, 2012, and

(c) U.S. patent application Ser. No. 14/622,969 filed Feb. 16, 2015 (nowU.S. Pat. No. 9,820,283, issued Nov. 14, 2017), which is a continuationof U.S. patent application Ser. No. 13/862,430, filed Apr. 14, 2013 (nowU.S. Pat. No. 8,995,381, issued Mar. 31, 2015), which claims the benefitof U.S. Provisional Application No. 61/625,078, filed Apr. 16, 2012,U.S. Provisional Application No. 61/661,361, filed Jun. 19, 2012, andU.S. Provisional Application No. 61/700,869, filed Sep. 13, 2012.

Each of the above is hereby incorporated by reference in its entirety.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Examples of several of the various embodiments of the present inventionare described herein with reference to the drawings, in which:

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present invention;

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers in a carrier group as per an aspect of anembodiment of the present invention;

FIG. 3 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present invention;

FIG. 4 is a block diagram of a base station and a wireless device as peran aspect of an embodiment of the present invention;

FIG. 5 is a diagram depicting uplink transmission timing of one or morecells in a first timing advance group (TAG) and a second TAG as per anaspect of an embodiment of the present invention;

FIG. 6 is an example message flow in a random access process in asecondary TAG as per an aspect of an embodiment of the presentinvention;

FIG. 7 shows example TAG configurations as per an aspect of anembodiment of the present invention;

FIG. 8 is an illustration of example uplink-downlink timing relation asper an aspect of an embodiment of the present invention;

FIG. 9 is an illustration of a cell group timing process in a wirelessdevice for as per an aspect of an embodiment of the present invention;

FIG. 10 is an illustration of a cell group timing process in a basestation for as per an aspect of an embodiment of the present invention;

FIG. 11 shows example transmission scenarios in a wireless network;

FIG. 12 is an example illustration of parallel transmission of SRS andother physical channel signals as per an aspect of an embodiment of thepresent invention;

FIG. 13 is an example illustration of parallel transmission of SRS andother physical channel signals as per an aspect of an embodiment of thepresent invention;

FIG. 14 is an illustration of power limitations during timing overlapbetween different subframes from different TAGs as per an aspect of anembodiment of the present invention.

FIG. 15 is an example illustration of parallel transmission of SRS andPUCCH/PUSCH as per an aspect of an embodiment of the present invention;

FIG. 16 is an example illustration of parallel transmission of SRS andPUCCH/PUSCH, and transient period as per an aspect of an embodiment ofthe present invention;

FIG. 17 is an example illustration of parallel transmission ofPUCCH/PUSCH and PUSCH as per an aspect of an embodiment of the presentinvention;

FIG. 18 is an example illustration of parallel transmission ofPUCCH/PUSCH and PUSCH, and transient period as per an aspect of anembodiment of the present invention;

FIG. 19 depicts an example of the first parameter calculated over timeas per an aspect of an embodiment of the present invention;

FIG. 20 depicts a flow chart showing the tasks performed in a wirelessdevice as per an aspect of an embodiment of the present invention; and

FIG. 21 a claim flow showing the tasks performed in a wireless device asper an aspect of an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Example embodiments of the present invention enable operation ofmultiple timing advance groups. Embodiments of the technology disclosedherein may be employed in the technical field of multicarriercommunication systems. More particularly, the embodiments of thetechnology disclosed herein may relate to operation of multiple timingadvance groups.

Example embodiments of the invention may be implemented using variousphysical layer modulation and transmission mechanisms. Exampletransmission mechanisms may include, but are not limited to: CDMA (codedivision multiple access), OFDM (orthogonal frequency divisionmultiplexing), TDMA (time division multiple access), Wavelettechnologies, and/or the like. Hybrid transmission mechanisms such asTDMA/CDMA, and OFDM/CDMA may also be employed. Various modulationschemes may be applied for signal transmission in the physical layer.Examples of modulation schemes include, but are not limited to: phase,amplitude, code, a combination of these, and/or the like. An exampleradio transmission method may implement QAM (quadrature amplitudemodulation) using BPSK (binary phase shift keying), QPSK (quadraturephase shift keying), 16-QAM, 64-QAM, 256-QAM, and/or the like. Physicalradio transmission may be enhanced by dynamically or semi-dynamicallychanging the modulation and coding scheme depending on transmissionrequirements and radio conditions.

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present invention. As illustrated in thisexample, arrow(s) in the diagram may depict a subcarrier in amulticarrier OFDM system. The OFDM system may use technology such asOFDM technology, SC-OFDM (single carrier-OFDM) technology, or the like.For example, arrow 101 shows a subcarrier transmitting informationsymbols. FIG. 1 is for illustration purposes, and a typical multicarrierOFDM system may include more subcarriers in a carrier. For example, thenumber of subcarriers in a carrier may be in the range of 10 to 10,000subcarriers. FIG. 1 shows two guard bands 106 and 107 in a transmissionband. As illustrated in FIG. 1, guard band 106 is between subcarriers103 and subcarriers 104. The example set of subcarriers A 102 includessubcarriers 103 and subcarriers 104. FIG. 1 also illustrates an exampleset of subcarriers B 105. As illustrated, there is no guard band betweenany two subcarriers in the example set of subcarriers B 105. Carriers ina multicarrier OFDM communication system may be contiguous carriers,non-contiguous carriers, or a combination of both contiguous andnon-contiguous carriers.

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers as per an aspect of an embodiment of the presentinvention. A multicarrier OFDM communication system may include one ormore carriers, for example, ranging from 1 to 10 carriers. Carrier A 204and carrier B 205 may have the same or different timing structures.Although FIG. 2 shows two synchronized carriers, carrier A 204 andcarrier B 205 may or may not be synchronized with each other. Differentradio frame structures may be supported for FDD (frequency divisionduplex) and TDD (time division duplex) duplex mechanisms. FIG. 2 showsan example FDD frame timing. Downlink and uplink transmissions may beorganized into radio frames 201. In this example, radio frame durationis 10 msec. Other frame durations, for example, in the range of 1 to 100msec may also be supported. In this example, each 10 msec radio frame201 may be divided into ten equally sized subframes 202. Other subframedurations such as including 0.5 msec, 1 msec, 2 msec, and 5 msec mayalso be supported. Subframe(s) may consist of two or more slots 206. Forthe example of FDD, 10 subframes may be available for downlinktransmission and 10 subframes may be available for uplink transmissionsin each 10 msec interval. Uplink and downlink transmissions may beseparated in the frequency domain. Slot(s) may include a plurality ofOFDM symbols 203. The number of OFDM symbols 203 in a slot 206 maydepend on the cyclic prefix length and subcarrier spacing.

FIG. 3 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present invention. The resource grid structure intime 304 and frequency 305 is illustrated in FIG. 3. The quantity ofdownlink subcarriers or resource blocks (RB) (in this example 6 to 100RBs) may depend, at least in part, on the downlink transmissionbandwidth 306 configured in the cell. The smallest radio resource unitmay be called a resource element (e.g. 301). Resource elements may begrouped into resource blocks (e.g. 302). Resource blocks may be groupedinto larger radio resources called Resource Block Groups (RBG) (e.g.303). The transmitted signal in slot 206 may be described by one orseveral resource grids of a plurality of subcarriers and a plurality ofOFDM symbols. Resource blocks may be used to describe the mapping ofcertain physical channels to resource elements. Other pre-definedgroupings of physical resource elements may be implemented in the systemdepending on the radio technology. For example, 24 subcarriers may begrouped as a radio block for a duration of 5 msec. In an illustrativeexample, a resource block may correspond to one slot in the time domainand 180 kHz in the frequency domain (for 15 kHz subcarrier bandwidth and12 subcarriers).

FIG. 4 is an example block diagram of a base station 401 and a wirelessdevice 406, as per an aspect of an embodiment of the present invention.A communication network 400 may include at least one base station 401and at least one wireless device 406. The base station 401 may includeat least one communication interface 402, at least one processor 403,and at least one set of program code instructions 405 stored innon-transitory memory 404 and executable by the at least one processor403. The wireless device 406 may include at least one communicationinterface 407, at least one processor 408, and at least one set ofprogram code instructions 410 stored in non-transitory memory 409 andexecutable by the at least one processor 408. Communication interface402 in base station 401 may be configured to engage in communicationwith communication interface 407 in wireless device 406 via acommunication path that includes at least one wireless link 411.Wireless link 411 may be a bi-directional link. Communication interface407 in wireless device 406 may also be configured to engage in acommunication with communication interface 402 in base station 401. Basestation 401 and wireless device 406 may be configured to send andreceive data over wireless link 411 using multiple frequency carriers.According to some of the various aspects of embodiments, transceiver(s)may be employed. A transceiver is a device that includes both atransmitter and receiver. Transceivers may be employed in devices suchas wireless devices, base stations, relay nodes, and/or the like.Example embodiments for radio technology implemented in communicationinterface 402, 407 and wireless link 411 are illustrated in FIG. 1, FIG.2, and FIG. 3, and associated text.

An interface may be a hardware interface, a firmware interface, asoftware interface, and/or a combination thereof. The hardware interfacemay include connectors, wires, electronic devices such as drivers,amplifiers, and/or the like. A software interface may include codestored in a memory device to implement protocol(s), protocol layers,communication drivers, device drivers, combinations thereof, and/or thelike. A firmware interface may include a combination of embeddedhardware and code stored in and/or in communication with a memory deviceto implement connections, electronic device operations, protocol(s),protocol layers, communication drivers, device drivers, hardwareoperations, combinations thereof, and/or the like.

The term configured may relate to the capacity of a device whether thedevice is in an operational or non-operational state. Configured mayalso refer to specific settings in a device that effect the operationalcharacteristics of the device whether the device is in an operational ornon-operational state. In other words, the hardware, software, firmware,registers, memory values, and/or the like may be “configured” within adevice, whether the device is in an operational or nonoperational state,to provide the device with specific characteristics. Terms such as “acontrol message to cause in a device” may mean that a control messagehas parameters that may be used to configure specific characteristics inthe device, whether the device is in an operational or non-operationalstate.

According to some of the various aspects of embodiments, an LTE networkmay include many base stations, providing a user plane (PDCP: packetdata convergence protocol/RLC: radio link control/MAC: media accesscontrol/PHY: physical) and control plane (RRC: radio resource control)protocol terminations towards the wireless device. The base station(s)may be interconnected with other base station(s) by means of an X2interface. The base stations may also be connected by means of an S1interface to an EPC (Evolved Packet Core). For example, the basestations may be interconnected to the MME (Mobility Management Entity)by means of the S 1-MME interface and to the Serving Gateway (S-GW) bymeans of the S1-U interface. The S1 interface may support a many-to-manyrelation between MMEs/Serving Gateways and base stations. A base stationmay include many sectors for example: 1, 2, 3, 4, or 6 sectors. A basestation may include many cells, for example, ranging from 1 to 50 cellsor more. A cell may be categorized, for example, as a primary cell orsecondary cell. When carrier aggregation is configured, a wirelessdevice may have one RRC connection with the network. At RRC connectionestablishment/re-establishment/handover, one serving cell may providethe NAS (non-access stratum) mobility information (e.g. TAI-trackingarea identifier), and at RRC connection re-establishment/handover, oneserving cell may provide the security input. This cell may be referredto as the Primary Cell (PCell). In the downlink, the carriercorresponding to the PCell may be the Downlink Primary Component Carrier(DL PCC), while in the uplink, it may be the Uplink Primary ComponentCarrier (UL PCC). Depending on wireless device capabilities, SecondaryCells (SCells) may be configured to form together with the PCell a setof serving cells. In the downlink, the carrier corresponding to an SCellmay be a Downlink Secondary Component Carrier (DL SCC), while in theuplink, it may be an Uplink Secondary Component Carrier (UL SCC). AnSCell may or may not have an uplink carrier.

A cell, comprising a downlink carrier and optionally an uplink carrier,is assigned a physical cell ID and a cell index. A carrier (downlink oruplink) belongs to only one cell, the cell ID or Cell index may alsoidentify the downlink carrier or uplink carrier of the cell (dependingon the context it is used). In the specification, cell ID may be equallyreferred to a carrier ID, and cell index may be referred to carrierindex. In implementation, the physical cell ID or cell index may beassigned to a cell. Cell ID may be determined using the synchronizationsignal transmitted on a downlink carrier. Cell index may be determinedusing RRC messages. For example, when the specification refers to afirst physical cell ID for a first downlink carrier, it may mean thefirst physical cell ID is for a cell comprising the first downlinkcarrier. The same concept may apply to, for example, carrier activation.When the specification indicates that a first carrier is activated, itequally means that the cell comprising the first carrier is activated.

Embodiments may be configured to operate as needed. The disclosedmechanism may be performed when certain criteria are met, for example,in wireless device, base station, radio environment, network, acombination of the above, and/or the like. Example criteria may bebased, at least in part, on for example, traffic load, initial systemset up, packet sizes, traffic characteristics, a combination of theabove, and/or the like. When the one or more criteria are met, theexample embodiments may be applied. Therefore, it may be possible toimplement example embodiments that selectively implement disclosedprotocols.

Example embodiments of the invention may enable operation of multipletiming advance groups. Other example embodiments may comprise anon-transitory tangible computer readable media comprising instructionsexecutable by one or more processors to cause operation of multipletiming advance groups. Yet other example embodiments may comprise anarticle of manufacture that comprises a non-transitory tangible computerreadable machine-accessible medium having instructions encoded thereonfor enabling programmable hardware to cause a device (e.g. wirelesscommunicator, UE, base station, etc.) to enable operation of multipletiming advance groups. The device may include processors, memory,interfaces, and/or the like. Other example embodiments may comprisecommunication networks comprising devices such as base stations,wireless devices (or user equipment: UE), servers, switches, antennas,and/or the like.

According to some of the various aspects of embodiments, serving cellshaving an uplink to which the same time alignment (TA) applies may begrouped in a TA group (TAG). Serving cells in one TAG may use the sametiming reference. For a given TAG, a user equipment (UE) may use onedownlink carrier as the timing reference at a given time. The UE may usea downlink carrier in a TAG as the timing reference for that TAG. For agiven TAG, a UE may synchronize uplink subframe and frame transmissiontiming of the uplink carriers belonging to the same TAG. According tosome of the various aspects of embodiments, serving cells having anuplink to which the same TA applies may correspond to the serving cellshosted by the same receiver. A TA group may comprise at least oneserving cell with a configured uplink. A UE supporting multiple TAs maysupport two or more TA groups. One TA group may contain the PCell andmay be called a primary TAG (pTAG). In a multiple TAG configuration, atleast one TA group may not contain the PCell and may be called asecondary TAG (sTAG). Carriers within the same TA group may use the sameTA value and the same timing reference.

FIG. 5 is a diagram depicting uplink transmission timing of one or morecells in a first timing advance group (TAG1) and a second TAG (TAG2) asper an aspect of an embodiment of the present invention. TAG1 mayinclude one or more cells, TAG2 may also include one or more cells. TAGtiming difference in FIG. 5 may be the difference in UE uplinktransmission timing for uplink carriers in TAG1 and TAG2. The timingdifference may range between, for example, sub micro-seconds to about 30micro-seconds.

FIG. 7 shows example TAG configurations as per an aspect of anembodiment of the present invention. In Example 1, pTAG include PCell,and sTAG includes SCell1. In Example 2, pTAG includes PCell and SCell1,and sTAG includes SCell2 and SCell3. In Example 3, pTAG includes PCelland SCell1, and sTAG1 includes SCell2 and SCell3, and sTAG2 includesSCell4. Up to four TAGs may be supported and other example TAGconfigurations may also be provided. In many examples of thisdisclosure, example mechanisms are described for a pTAG and an sTAG. Theoperation with one example sTAG is described, and the same operation maybe applicable to other sTAGs. The example mechanisms may be applied toconfigurations with multiple sTAGs.

According to some of the various aspects of embodiments, TA maintenance,pathloss reference handling and the timing reference for pTAG may followLTE release 10 principles. The UE may need to measure downlink pathlossto calculate the uplink transmit power. The pathloss reference may beused for uplink power control and/or transmission of random accesspreamble(s). A UE may measure downlink pathloss using the signalsreceived on the pathloss reference cell. For SCell(s) in a pTAG, thechoice of pathloss reference for cells may be selected from and belimited to the following two options: a) the downlink SCell linked to anuplink SCell using the system information block 2 (SIB2), and b) thedownlink PCell. The pathloss reference for SCells in pTAG may beconfigurable using RRC message(s) as a part of SCell initialconfiguration and/or reconfiguration. According to some of the variousaspects of embodiments, PhysicalConfigDedicatedSCell information element(IE) of an SCell configuration may include the pathloss reference SCell(downlink carrier) for an SCell in pTAG. The downlink SCell linked to anuplink SCell using the system information block 2 (SIB2) may be referredto as the SIB2 linked downlink of the SCell. Different TAGs may operatein different bands. For an uplink carrier in an sTAG, the pathlossreference may be only configurable to the downlink SCell linked to anuplink SCell using the system information block 2 (SIB2) of the SCell.

To obtain initial uplink (UL) time alignment for an sTAG, eNB mayinitiate an RA procedure. In an sTAG, a UE may use one of any activatedSCells from this sTAG as a timing reference cell. In an exampleembodiment, the timing reference for SCells in an sTAG may be the SIB2linked downlink of the SCell on which the preamble for the latest RAprocedure was sent. There may be one timing reference and one timealignment timer (TAT) per TA group. TAT for TAGs may be configured withdifferent values. When the TAT associated with the pTAG expires: allTATs may be considered as expired, the UE may flush all HARQ buffers ofall serving cells, the UE may clear any configured downlinkassignment/uplink grants, and the RRC in the UE may release PUCCH/SRSfor all configured serving cells. When the pTAG TAT is not running, ansTAG TAT may not be running. When the TAT associated with sTAG expires:a) SRS transmissions may be stopped on the corresponding SCells, b) SRSRRC configuration may be released, c) CSI reporting configuration forthe corresponding SCells may be maintained, and/or d) the MAC in the UEmay flush the uplink HARQ buffers of the corresponding SCells.

Upon deactivation of the last SCell in an sTAG, the UE may not stop TATof the sTAG. In an implementation, upon removal of the last SCell in ansTAG, TAT of the TA group may not be running. RA procedures in parallelmay not be supported for a UE. If a new RA procedure is requested(either by UE or network) while another RA procedure is already ongoing,it may be up to the UE implementation whether to continue with theongoing procedure or start with the new procedure. The eNB may initiatethe RA procedure via a PDCCH order for an activated SCell. This PDCCHorder may be sent on the scheduling cell of this SCell. When crosscarrier scheduling is configured for a cell, the scheduling cell may bedifferent than the cell that is employed for preamble transmission, andthe PDCCH order may include the SCell index. At least a non-contentionbased RA procedure may be supported for SCell(s) assigned to sTAG(s).

FIG. 6 is an example message flow in a random access process in asecondary TAG as per an aspect of an embodiment of the presentinvention. eNB transmits an activation command 600 to activate an SCell.A preamble 602 (Msg1) may be sent by a UE in response to the PDCCH order601 on an SCell belonging to an sTAG. In an example embodiment, preambletransmission for SCells may be controlled by the network using PDCCHformat 1A. Msg2 message 603 (RAR: random access response) in response tothe preamble transmission on SCell may be addressed to RA-RNTI in PCellcommon search space (CSS). Uplink packets 604 may be transmitted on theSCell, in which the preamble was transmitted.

According to some of the various aspects of embodiments, initial timingalignment may be achieved through a random access procedure. This mayinvolve the UE transmitting a random access preamble and the eNBresponding with an initial TA command NTA (amount of timing advance)within the random access response window. The start of the random accesspreamble may be aligned with the start of the corresponding uplinksubframe at the UE assuming N_(TA)=0. The eNB may estimate the uplinktiming from the random access preamble transmitted by the UE. The TAcommand may be derived by the eNB based on the estimation of thedifference between the desired UL timing and the actual UL timing. TheUE may determine the initial uplink transmission timing relative to thecorresponding downlink of the sTAG on which the preamble is transmitted.

A base station may communicate with a mix of wireless devices. Wirelessdevices may support multiple technologies, or multiple releases of thesame technology, have some specific capability depending on the wirelessdevice category and/or capability. A base station may comprise multiplesectors. When this disclosure refers to a base station communicatingwith a plurality of wireless devices, this disclosure may refer to asubset of the total wireless devices in the coverage area. Thisdisclosure may refer to, for example, a plurality of wireless devices ofa given LTE release with a given capability and in a given sector of thebase station. The plurality of wireless devices in this disclosure mayrefer to a selected plurality of wireless devices, and/or a subset oftotal wireless devices in the coverage area, which perform according tothe disclosed methods, and/or the like. There may be many wirelessdevices in the coverage area that may not comply with the disclosedmethods, for example, because those wireless devices perform based onolder releases of LTE technology. A time alignment command MAC controlelement may be a unicast MAC command transmitted to a wireless device.

According to some of the various aspects of various embodiments, thebase station or wireless device may group cells into a plurality of cellgroups. The term “cell group” may refer to a timing advance group (TAG)or a timing alignment group or a time alignment group. Time alignmentcommand may also be referred to timing advance command. A cell group mayinclude at least one cell. A MAC TA command may correspond to a TAG. Acell group may explicitly or implicitly be identified by a TAG index.Cells in the same band may belong to the same cell group. A first cell'sframe timing may be tied to a second cell's frame timing in a TAG. Whena time alignment command is received for the TAG, the frame timing ofboth first cell and second cell may be adjusted. Base station(s) mayprovide TAG configuration information to the wireless device(s) by RRCconfiguration message(s).

The mapping of a serving cell to a TAG may be configured by the servingeNB with RRC signaling. The mechanism for TAG configuration andreconfiguration may be based on RRC signaling. According to some of thevarious aspects of embodiments, when an eNB performs SCell additionconfiguration, the related TAG configuration may be configured for theSCell. In an example embodiment, eNB may modify the TAG configuration ofan SCell by removing (releasing) the SCell and adding (configuring) anew SCell (with the same physical cell ID and frequency) with an updatedTAG ID. The new SCell with the updated TAG ID may be initially inactivesubsequent to being assigned the updated TAG ID. eNB may activate theupdated new SCell and then start scheduling packets on the activatedSCell. In an example implementation, it may not be possible to changethe TAG associated with an SCell, but rather, the SCell may need to beremoved and a new SCell may need to be added with another TAG. Forexample if there is a need to move an SCell from an sTAG to a pTAG, atleast one RRC message, for example, at least one RRC reconfigurationmessage, may be send to the UE to reconfigure TAG configurations byreleasing the SCell and then configuring the SCell as a part of pTAG(when an SCell is added/configured without a TAG index, the SCell isexplicitly assigned to pTAG). The PCell may not change its TA group andmay always be a member of the pTAG.

An eNB may perform initial configuration based on initial configurationparameters received from a network node (for example a managementplatform), an initial eNB configuration, a UE location, a UE type, UECSI feedback, UE uplink transmissions (for example, data, SRS, and/orthe like), a combination of the above, and/or the like. For example,initial configuration may be based on UE channel state measurements orreceived signal timing. For example, depending on the signal strengthreceived from a UE on various SCells downlink carrier or bydetermination of UE being in a repeater coverage area, or a combinationof both, an eNB may determine the initial configuration of sTAGs andmembership of SCells to sTAGs.

In an example implementation, the TA value of a serving cell may change,for example due to UE's mobility from a macro-cell to a repeater or anRRH (remote radio head) coverage area. The signal delay for that SCellmay become different from the original value and different from otherserving cells in the same TAG. In this scenario, eNB may re-configurethis TA-changed serving cell to another existing TAG. Or alternatively,the eNB may create a new TAG for the SCell based on the updated TAvalue. The TA value may be derived, for example, through eNBmeasurement(s) of signal reception timing, a RA mechanism, or otherstandard or proprietary processes. An eNB may realize that the TA valueof a serving cell is no longer consistent with its current TAG. Theremay be many other scenarios which require eNB to reconfigure TAGs.During reconfiguration, the eNB may need to move the reference SCellbelonging to an sTAG to another TAG. In this scenario, the sTAG wouldrequire a new reference SCell. In an example embodiment, the UE mayselect an active SCell in the sTAG as the reference timing SCell.

eNB may consider UE's capability in configuring multiple TAGs for a UE.UE may be configured with a configuration that is compatible with UEcapability. Multiple TAG capability may be an optional feature and perband combination Multiple TAG capability may be introduced. UE maytransmit its multiple TAG capability to eNB via an RRC message and eNBmay consider UE capability in configuring TAG configuration(s).

The purpose of an RRC connection reconfiguration procedure may be tomodify an RRC connection, (e.g. to establish, modify and/or release RBs,to perform handover, to setup, modify, and/or release measurements, toadd, modify, and/or release SCells). If the received RRC ConnectionReconfiguration message includes the sCellToReleaseList, the UE mayperform an SCell release. If the received RRC Connection Reconfigurationmessage includes the sCellToAddModList, the UE may perform SCelladditions or modification.

The parameters related to SCell random access channel may be common toall UEs. For example, PRACH configuration (RACH resources, configurationparameters, RAR window) for the SCell may be common to UEs. RACHresource parameters may include prach-configuration index, and/orprach-frequency offset. SCell RACH common configuration parameters mayalso include power: power ramping parameter(s) for preambletransmission; and max number of preamble transmission parameter. It ismore efficient to use common parameters for RACH configuration, sincedifferent UEs will share the same random access channel.

eNB may transmit at least one RRC message to configure PCell, SCell(s)and RACH, and TAG configuration parameters. MAC-MainConfig may include atimeAlignmentTimerDedicated IE to indicate time alignment timer valuefor the pTAG. MAC-MainConfig may further include an IE including asequence of at least one (sTAG ID, and TAT value) to configure timealignment timer values for sTAGs. In an example, a first RRC message mayconfigure TAT value for pTAG, a second RRC message may configure TATvalue for sTAG1, and a third RRC message may configure TAT value forsTAG2. There is no need to include all the TAT configurations in asingle RRC message. In an example embodiment they may be included in oneor two RRC messages. The IE including a sequence of at least one (sTAGID, and TAT) value may also be used to update the TAT value of anexisting sTAG to an updated TAT value. The at least one RRC message mayalso include sCellToAddModList including at least one SCellconfiguration parameters. The radioResourceConfigDedicatedSCell(dedicated radio configuration IEs) in sCellToAddModList may include anSCell MAC configuration comprising TAG ID for the corresponding SCelladded or modified. The radioResourceConfigDedicatedSCell may alsoinclude pathloss reference configuration for an SCell. If TAG ID is notincluded in SCell configuration, the SCell is assigned to the pTAG. Inother word, a TAG ID may not be included inradioResourceConfigDedicatedSCell for SCells assigned to pTAG. TheradioResourceConfigCommonSCell (common radio configuration IEs) insCellToAddModList may include RACH resource configuration parameters,preamble transmission power control parameters, and other preambletransmission parameter(s). At the least one RRC message configuresPCell, SCell, RACH resources, and/or SRS transmissions and may assigneach SCell to a TAG (implicitly for pTAG or explicitly for sTAG). PCellis always assigned to the pTAG.

According to some of the various aspects of embodiments, a base stationmay transmit at least one control message to a wireless device in aplurality of wireless devices. The at least one control message is forexample, RRC connection reconfiguration message, RRC connectionestablishment message, RRC connection re-establishment message, and/orother control messages configuring or reconfiguring radio interface,and/or the like. The at least one control message may be configured tocause, in the wireless device, configuration of at least: I) a pluralityof cells. Each cell may comprise a downlink carrier and zero or oneuplink carrier. The configuration may assign a cell group index to acell in the plurality of cells. The cell group index may identify one ofa plurality of cell groups. A cell group in the plurality of cell groupsmay comprise a subset of the plurality of cells. The subset may comprisea reference cell with a reference downlink carrier and a referenceuplink carrier. Uplink transmissions by the wireless device in the cellgroup may employ the reference cell (the primary cell in pTAG and asecondary cell in an sTAG). The wireless device may employ asynchronization signal transmitted on the reference downlink carrier astiming reference to determine a timing of the uplink transmissions. Thesynchronization signal for example may be a) primary/secondarysynchronization signal, b) reference signal(s), and/or c) a combinationof a) and b). II) a time alignment timer for each cell group in theplurality of cell groups; and/or III) an activation timer for eachconfigured secondary cell.

The base station may transmit a plurality of timing advance commands.Each timing advance command may comprise: a time adjustment value, and acell group index. A time alignment timer may start or may restart whenthe wireless device receives a timing advance command to adjust uplinktransmission timing on a cell group identified by the cell group index.A cell group may be considered out-of-sync, by the wireless device, whenthe associated time alignment timer expires or is not running. The cellgroup may be considered in-sync when the associated time alignment timeris running.

The timing advance command may causes substantial alignment of receptiontiming of uplink signals in frames and subframes of all activated uplinkcarriers in the cell group at the base station. The time alignment timervalue may be configured as one of a finite set of predetermined values.For example, the finite set of predetermined values may be eight. Eachtime alignment timer value may be encoded employing three bits. TAG TATmay be a dedicated time alignment timer value and is transmitted by thebase station to the wireless device. TAG TAT may be configured to causeconfiguration of time alignment timer value for each time alignmentgroup. The IE TAG TAT may be used to control how long the UE isconsidered uplink time aligned. It corresponds to the timer for timealignment for each cell group. Its value may be in number of subframes.For example, value sf500 corresponds to 500 subframes, sf750 correspondsto 750 subframes and so on. An uplink time alignment is common for allserving cells belonging to the same cell group. In an exampleembodiment, the IE TAG TAT may be defined as: TAG TAT::=SEQUENCE{TAG ID,ENUMERATED {sf500, sf750, sf1280, sf1920, sf2560, sf5120, sf10240,infinity}}. Time alignment timer for pTAG may be indicated in a separateIE and may not be included in the sequence.

In an example, TimeAlignmentTimerDedicated IE may be sf500, and then TAGTAT may be {1, sf500; 2, sf2560; 3, sf500}. In the example, timealignment timer for the pTAG is configured separately and is notincluded in the sequence. In the examples, TAG0 (pTAG) time alignmenttimer value is 500 subframes (500 msec), TAG1 (sTAG) time alignmenttimer value is 500 subframes, TAG2 time alignment timer value is 2560subframes, and TAG3 time alignment timer value is 500 subframes. This isfor example purposes only. In this example a TAG may take one of 8predefined values. In a different embodiment, the enumerated valuescould take other values.

According to aspects of some of the various embodiments, upon receptionof a timing advance command for a given timing advance group, the UE mayadjust its uplink transmission timing for PUCCH/PUSCH/SRS of the servingcells belonging to the timing advance group. The timing advance commandmay indicate the change of the uplink timing of the timing advance grouprelative to the current uplink timing of the timing advance group, forexample, as multiples of 16^(T) ^(s) . ^(T) ^(s) may, for example, bethe sampling duration, for example, 16 ^(T) ^(s) =16*10/307,200msec=0.52 micro-seconds. In some embodiments, ^(T) ^(s) may be analternative duration, for example, a clocking duration.

According to some of the various aspects of embodiments, in a randomaccess response with an 11-bit timing advance command, TA, may indicateN_(TA) values by index values of TA=0, 1, 2, . . . , 1282, where anamount of the time alignment may be given by N_(TA)=TA×16. N_(TA) may bemaintained on a per-timing advance group basis. In other cases involvinga 6-bit timing advance command, TA for a timing advance group mayindicate an adjustment of the current N_(TA) value, N_(TA,old), to a newN_(TA) value for the timing advance group, N_(TA,new). The adjustmentmay be by index values of TA=0, 1, 2, . . . , 63, whereN_(TA,new)=N_(TA,old)+(TA−31)×16. Adjustment of a N_(TA) value by apositive or a negative amount may indicate advancing or delaying theuplink transmission timing by a given amount respectively.

According to some of the various embodiments, for a timing advancecommand received on subframe n, the corresponding adjustment of thetiming may apply from the beginning of, for example, subframe n+6. Whenthe UE's uplink PUCCH/PUSCH/SRS transmissions in subframe n and subframen+1 of a serving cell are overlapped due to the timing adjustment, theUE may transmit complete subframe n of the serving cell and may nottransmit the overlapped part of subframe n+1 of the serving cell. For atiming advance group, if the received downlink reference timing changesand/or is not compensated and/or is partly compensated by the uplinktiming adjustment without a timing advance command, the UE may changeN_(TA) of the timing advance group accordingly.

FIG. 8 is an illustration of example Uplink-downlink timing relation asper an aspect of an embodiment of the present invention. Transmission ofthe uplink radio frame number i from the UE may start(N_(TA)+N_(TA offset))×T_(s) seconds before the start of thecorresponding downlink radio frame at the UE, where, for example:0≤N_(TA)≤20512, N_(TA offset)=0 for frame structure type 1 and, forexample, N_(TA offset)=624 for frame structure type 2. Other examplesincluding other values and ranges may also be configured. Not all slotsin a radio frame may be transmitted. One example is TDD where a subsetof the slots in a radio frame may be transmitted.

A UE receiver may cope with a relative propagation delay difference upto a threshold, for example 30 μs, among the component carriers to beaggregated, for example, in inter-band non-contiguous carrieraggregation (CA). The carriers with a relative propagation delaydifference may belong to different TAGs. The base station time alignmentmay be within a threshold, for example 1.3 μs. In the example, a UE maycope with a delay spread of up to 31.3 μs among the component carriersmonitored at the receiver.

In prior releases of LTE technology (for example, release 10), uplinktransmission on uplink carriers may be aligned and use the same timingreference, and a PCell may be employed as the timing reference. Inrelease 11 or above, multiple TAGs may be supported, and a TAG may haveits own time alignment process. Uplink subframe transmissions indifferent TAGs may have a timing difference. A UE may be able to copewith a timing difference within a certain limit, for example 31.3 μs. Ifthe timing difference between different TAGs in a given scenarioincreases beyond the allowed limit, network performance may deteriorate,and/or unwanted interference may increase. FIG. 5 is an illustration ofthe timing difference between two TAGs as per an aspect of an embodimentof the present invention. This may apply to uplink transmission timingand/or downlink reception timing in a UE. Timing delay in excess of agiven threshold, for example, a delay of 80 μs>33.3 μs, may cause anoverlap between different symbols of different carriers in a subframe inuplink transmission. This overlap may cause distortions in UE transmitpower, for example, around the subframe boundaries and when UE is powerlimited in the uplink transmission. There may be a need to address thisissue and develop an eNB and/or UE behavior that addresses this issueand reduce the negative effects of such a scenario. This issue may notapply to prior releases of LTE technology (for example, release 10)since uplink transmission timing may be aligned on uplink carriers.There may be a need to reduce the possibility of an excessive TAG timingdifference in a network.

According to some of the various aspects of embodiments, an eNB may keeptrack of timing differences between different TAGs. This could beperformed using one or a combination of the methods in an eNB, forexample: by monitoring uplink reception timings; monitoring reception ofuplink preambles transmitted by a UE; by keeping track of and/oraccumulating transmitted TA values in TA commands; by measuring and/orestimating propagation delay or round-trip delay for TAGs; and/or thelike. An eNB may know the uplink transmission timing difference and/orrelative propagation delay difference between different TAGs. An eNB maycalculate the uplink transmission timing by accumulating the transmittedTA commands (including RAR) and detect excess timing differences betweendifferent TAGs. When a timing difference exceeds a threshold, forexample 30 μsec or 31.3 μsec, an eNB may perform an action to reduce theoccurrence of unwanted effects of excessive timing differences. Forexample, an eNB may take one or a combination of the following actions:the eNB may stop scheduling uplink transmissions on some of the TAG(s);the eNB may de-configure SCell(s) or uplink SCell carriers in some ofthe TAG(s); the eNB may deactivate some of the SCells in some of theTAG(s); the eNB may de-configure TAG configuration of some of theSCell(s); the eNB may initiate a random access process in one of theSCells; and/or the like. The eNB may perform one or many of theseactions to reduce the effect of excessive delay between multiple TAGs,and may reduce the interference and/or deterioration in UE performance.One or more carriers with excessive delay may be re-configured (orde-configured) at a MAC and/or RRC level to reduce excessive time delaybetween carriers in a UE.

According to some of the various aspects of embodiments, a UE may takean action to avoid an excessive timing delay between multiple TAGs. Anexcessive timing delay between TAGs may apply to downlink receptiontiming and/or uplink transmission timing. In an example embodiment, aneNB may not be able to track the uplink transmission timing differenceamong TAGs. For a timing advance group, if the received downlinkreference timing changes and/or a timing change is not compensated by TAcommands, and/or a timing change is partly compensated by an uplinktiming adjustment without a timing advance command, the UE may changeN_(TA) of the timing advance group accordingly. An eNB may not be ableto accurately track the timing difference between uplink transmissionsof various TAGs in one or more scenarios. The understanding oftransmission time differences between uplink component carriers indifferent TAGs may be different from an UE and an eNB. Therefore, an eNBmay transmit a TA command to a UE, which may result in excessive uplinktransmission timing differences between different TAGs. For example, aTA command may increase the transmission timing difference betweencarriers in different TAGs to above a threshold value, for example 30μs, or 31.3 μs, etc. In another example embodiment, the timingdifference between received signals from reference signals belonging totwo TAGs may exceeds a threshold. In another example embodiment, inorder to maintain uplink synchronization, a UE may need to change TAGuplink transmission timings such that it may result in excessive timingdifferences between TAGs.

According to some of the various aspects of embodiments, when the timingdifference exceeds a threshold or would exceed a threshold due to areceived TA command or due to UE's detection of changes in timingreference, a UE may perform an action to reduce the occurrence ofunwanted effects of excessive timing differences. For example, a UE maytake one or a combination of the following actions. In an exampleembodiment, if the TA command is for the pTAG, the UE may adjust thepTAG timing, and if timing difference between TAGs (for example a pTAGand an sTAG) exceeds the threshold, the UE may put the sTAG(s) in anout-of-sync state and stop uplink transmissions in sTAG(s) withexcessive time differences. If a TA command is for an sTAG and resultsin excess time differences between the sTAG and the pTAG, the UE may notadjust uplink transmission according to a TA command. The UE may changethe state of the sTAG to an out-of-sync state. If a TA command is for ansTAG and results in excess time differences between the sTAG and anothersTAG, the UE may take one of the following two actions: a) the UE maynot adjust uplink transmission according to a TA command and the UE maychange the state of the sTAG to an out-of-sync state; and b) the UE mayadjust the uplink transmission according to a TA command and the UE maychange the state of the other sTAGs with excessive time differences toan out-of-sync state.

According to some of the various aspects of embodiments, if a TA commandresults in excess time differences between TAGs, the UE may abort theexecution of the TA command. A base station may notice that the uplinktiming is not updated according to a TA command, and detect an uplinkout-of-sync cell (or TAG). The base station may take a proper actionaccording to the previous paragraph. In an example, the UE may alsochange the state of the TAG to an out-of-sync state. In another exampleembodiment, the UE may adjust its uplink transmission timing for a pTAGwhen a TA command for the pTAG is received. If the UE observes that theuplink transmission timing between an sTAG and a pTAG or between twosTAGs exceed a threshold, the UE may take an action. For example, the UEmay change the state of an sTAG to an out-of-sync state, or the UE mayinform an eNB that a radio link issue exists. This could be done bytransmitting a MAC or an RRC message to a base station. In anotherexample embodiment, a UE may check the timing difference as a result ofa timing adjustment when the UE receives a TA and/or when uplink timingis adjusted autonomously by the UE, and the UE may adjust the TA up to amaximum amount. In this case, the timing difference between TAGs may notexceed a threshold amount. If an event that would result in an excessiveuplink transmission timing difference, a UE may take an action toprevent unwanted effects.

A UE may know the timing difference between its configured cells. In anexample embodiment, when the UE detects an excessive delay difference ina cell, the UE may report a channel quality index (CQI) index of 0 (outof range) for these cells that are beyond the receive window to an eNB.This may make it possible to indicate cells that have already fallen outof the receive window to an eNB. There may be several other reasons forthe UE to send a CQI 0, and the eNB may not know exactly why the UE issending a CQI equal to zero. It may be up to an eNB implementation toevaluate this CQI value correctly and to take an action. In anotherexample embodiment, a mechanism may be considered that informs the eNBof cells that exceed a predefined propagation delay difference. The eNBmay take an action and may deactivate or reconfigure these cell(s). Inanother example embodiment, the eNB may detect the timing difference andtake a protocol layer one/two or higher layer (for example RRC) actionto remedy the situation. The eNB action may be an RRC or MAC action andmay comprise at least one of the following: de-configuring a cell,de-activating a cell, initiating a random access process, not schedulinguplink packets on a cell, and transmitting an RRC reconfigurationmessage to said wireless device.

According to some of the various aspects of embodiments, a UE maymonitor the time difference between reference signals of differentreceiving reference signals and take proper action when the time delayexceeds a threshold. In this example, a UE may cope with a delay spreadof up to 31.3 μs among the component carriers monitored at the receiver.If a higher delay (TAG timing difference) is observed, the UE may takeone of many of the following actions: deactivate a carrier, change thesync state of a carrier, transmit a message (for example MAC or RRC) toa base station, and/or the like. If the downlink timing differencebetween two component carriers is increased above a threshold,additional UE complexity may be required because the UE may need tobuffer data for one of the two CCs (PCell or SCell) during the timedifference between the PCell and the SCell. That may also result incomplexity and unwanted power limitations and/or interference in theuplink. In general, carrier aggregation may be more likely to bedeployed in urban areas than in rural areas in order to enhance bothcell capacity and peak throughput, and therefore, a relatively smallcell radius may be assumed. But in an example implementation, someactions may be taken by a UE and/or an eNB to reduce interference wherea cell radius is high and delay differences between bands may be high orradio wave reflections may result in excessive delay spread amongcarriers.

According to aspects of some of the various embodiments, a wirelessdevice may communicate employing a plurality of cells. FIG. 9 is anillustration of a cell group timing process in a wireless device for asper an aspect of an embodiment of the present invention. The wirelessdevice may receive at least one control message from a base station atblock 900. The at least one control message to cause in the wirelessdevice configuration of a primary cell and at least one secondary cellin the plurality of cells, and assignment of each of the at least onesecondary cell to a cell group in a plurality of cell groups. Theplurality of cell groups may comprise a primary cell group and asecondary cell group. The primary cell group may comprise a first subsetof the plurality of cells. The first subset may comprise the primarycell. Uplink transmissions by the wireless device in the primary cellgroup may employ a first synchronization signal transmitted on theprimary cell as a primary timing reference. The secondary cell group maycomprise a second subset of the at least one secondary cell. Uplinktransmissions in the secondary cell group may employ a secondsynchronization signal on an activated secondary cell in the secondarycell group as a secondary timing reference. The wireless device mayreceive at least one timing advance command from the base station atblock 902. The timing advance command may comprise a time adjustmentvalue; and an index identifying the secondary cell group.

The wireless device may apply the time adjustment value to uplinktransmission timing of the secondary cell group at block 904. Thewireless device may trigger an action in response to the wireless devicedetecting a difference between primary cell group timing and secondarycell group timing, the difference being greater than a threshold atblock 906. The threshold may be determined internally by the wirelessdevice or may be communicated to the wireless device. The threshold maydepend on many variables such as signal transmission power, powerlimitations, receiver signal processing capability, handset release,and/or the like. In an example embodiment, the threshold may be a fixedvalue for example 30 micro-seconds, or 20 micro-seconds. In anotherexample embodiment, the threshold may be calculated internally by themobile device (for example dynamically, semi-statically, statically,etc.) depending on various internal parameters and timers and may varydepending on the circumstances.

According to aspects of some of the various embodiments, there may bevarious methods to determine the timings. The primary cell group timingmay be a primary cell group uplink signal timing. The secondary cellgroup timing is a secondary cell group uplink signal timing. The primarycell group timing may be a primary cell group downlink signal timing.The secondary cell group timing may be a secondary cell group downlinksignal timing. In an example embodiment, the difference may employ, atleast in part, the first synchronization signal and the secondsynchronization signal. The wireless device may employ, at least inpart, primary cell group uplink signal timing and secondary cell groupuplink signal timing to detect the difference. Transmission of downlinksignals in the primary cell group and the secondary cell group may betime aligned within a predetermined value.

According to aspects of some of the various embodiments, the action maybe an action in a radio resource control layer or an action in a mediumaccess control layer. The action may comprise at least one of thefollowing: a) transmitting a radio resource control (RRC) message to thebase station. The RRC message may inform the base station that aninternal event has occurred, for example the RRC message may be aconnection re-establishment message or an error message. b) transmittinga medium access control message to the base station. The MAC message mayinform the base station about an error scenario or about an action. c)changing the synchronization state of a cell from an in-sync state to anout-of-sync state; and d) changing the synchronization state of a cellgroup from an in-sync state to an out-of-sync state; e) suspendinguplink transmission on a cell. For example, uplink transmission on acell that its timing difference is above the threshold may be stopped.The comparison may be made with the primary cell timing. f) suspendinguplink transmission on a cell group. For example, uplink transmission ona cell group that its timing difference is above the threshold may bestopped. The comparison may be made with the primary cell timing. g)ignoring a received timing advance command resulting in an increase inthe difference. Other actions may also possible.

According to aspects of some of the various embodiments, a base stationmay be configured communicate employing a plurality of cells. FIG. 10 isan illustration of a cell group timing process in a base station for asper an aspect of an embodiment of the present invention. The basestation may transmit at least one control message to a wireless deviceat block 1000. The at least one control message may cause in thewireless device configuration of a primary cell and at least onesecondary cell in the plurality of cells assignment of each of the atleast one secondary cell to a cell group in a plurality of cell groups.The plurality of cell groups may comprise a primary cell groupcomprising a first subset of the plurality of cells. The first subsetmay comprise the primary cell. Uplink transmissions by the wirelessdevice in the primary cell group may employ a first synchronizationsignal transmitted on the primary cell as a primary timing reference.The secondary cell group may comprise a second subset of the at leastone secondary cell. Uplink transmissions in the secondary cell group mayemploy a second synchronization signal on an activated secondary cell inthe secondary cell group as a secondary timing reference. The basestation may transmit at least one timing advance command to the wirelessdevice at 1002. The timing advance command may comprise a timeadjustment value and an index identifying the secondary cell group. Thebase station may trigger an action corresponding to the wireless devicein response to the base station detecting a difference between primarycell group timing of the wireless device and secondary cell group timingof the wireless device, the difference being greater than a threshold atblock 1004. The threshold may be determined internally by the basestation or may be communicated to the base station. The threshold maydepend on many variables such as signal transmission power, powerlimitations, receiver signal processing capability, handset or basestation release, and/or the like. In an example embodiment, thethreshold may be a fixed value for example 30 micro-seconds, or 20micro-seconds. In another example embodiment, the threshold may becalculated (for example dynamically, semi-statically, statically, etc.)internally by the mobile device depending on various internal parametersand timers and may vary depending on the circumstances.

The difference may be detected employing at least one random accessprocess. The difference may be detected employing the at least onetiming advance command. The action may be an action in a radio resourcecontrol layer or an action in a medium access control layer. The actionmay comprise at least one of the following: a) transmitting a mediumaccess control message to the wireless device; b) de-configuring atleast one cell; c) de-activating at least one cell; d) initiating arandom access process; e) not scheduling uplink packets on at least onecell; and f) transmitting a radio resource control reconfigurationmessage to the wireless device. Transmission of downlink signals in theprimary cell group and the secondary cell group may be time alignedwithin a predetermined value.

In prior releases of LTE technology (for example, release 10), uplinktransmission on uplink carriers may be aligned and use the same timingreference, and PCell may be employed as the timing reference. A randomaccess preamble transmission timing may be based on PCell referencesignal timing and considering TA=0. A random access response may include11-bit timing advance command, TA, and may indicate N_(TA) values byindex values of TA=0, 1, 2, . . . , 1282, where an amount of the timealignment may be given by N_(TA)=TA×16.

In release 11 or above multiple TAGs may be supported, and a TAG mayhave its own time alignment process. Uplink subframe transmission in aTAG may have its own timing difference. A UE receiver may cope with arelative propagation delay difference up to a certain limit, for example30 μs, among the component carriers to be aggregated, for example, ininter-band non-contiguous CA. The base station time alignment may be upto a certain limit, for example 1.3 μs. In the example, a UE may copewith a delay spread of up to 31.3 μs among the component carriersmonitored at the receiver. If the timing difference between differentTAGs in a given scenario increases beyond the allowed limit, networkperformance may deteriorate, and/or unwanted interference may increase.Therefore, network and/or equipment implementation may considerpreventing or reducing the possibility of introducing a timingdifference between TAGs above a given threshold.

The signal propagation and other delays including for example, repeaterdelay, etc. may be in the range of one micro-second to tens or hundredsof micro seconds. For example propagation time difference for radius of10 km may be 33.3 μs, and for a cell radius of 100 km may be 333 μs. Theround-trip delay time may be twice these values.

If the initial PRACH transmission considers TA=0, then the overlapbetween PRACH and other signals such as PUSCH, PUCCH, and/or SRS mayinclude a wide range including part of a subframe. The duration ofoverlap between PRACH transmission and PUSCH, PUCCH and/or SRS maydepend on radio transmission delay, including propagation delay (afunction of distance between UE and eNB), repeater delay, and otherfactors affecting the reception timing of reference signal transmittedby an eNB and received by a UE and used for preamble transmission. Theduration of overlap between PRACH transmission and PUSCH, PUCCH and/orSRS may also depend preamble duration. A wide range in overlap betweenPRACH and other uplink channels, may reduce efficiency for example whenthe UE is power limited.

There may be advantages in transmitting an initial preamble, which itstiming is closer to an sTAG adjusted uplink timing. This may result insmaller time alignment adjustments in random access response. Since thetiming difference between TAGs is typically smaller than theround-trip-delay, a UE may use the timing of other TAGs in transmittingthe first random access response. The UE may use another TAG's (forexample pTAG's) timing for uplink transmission, and use a non-zero valuefor TA for preamble transmission. The UE may use the timing of pTAG, orother synchronized sTAGs, or previous N_(TA) timing values in setting aproper value for TA. This process may be triggered if certain radioconfiguration or radio conditions arise. A UE may transmit preamble foran sTAG with a non-zero TA value. This may decrease the overlappossibilities between preamble and other uplink channels, and mayimprove power management process in a UE when a UE is power limited. Theinter TAG timing difference may be smaller than, for example 31.3 μs.The adjustment needed for the timing of the uplink preamble transmissionmay be below 31.3 μs. If TA=0 is used for uplink transmission, theadjustment may be up to hundreds of μs.

According to some of the various aspects of embodiments, when asecondary cell group is configured, it is initially in an out-of-syncstate and its time alignment timer may not be running. Uplinktransmission timing advance may be initialized as zero. A base stationmay start a random access process to synchronize uplink timing of thewireless device for the secondary cell group. The base station maytransmit a PDCCH order, and receive a random access preamble. The basestation may then transmit a random access response including a timingadvance command for the secondary cell group. The time alignment timerof the secondary cell group starts running and the secondary cell groupmay become in-sync after the wireless device receives and processes therandom access response. In an example embodiment, a method to initiallysynchronize the uplink transmission of a secondary cell group isinitiating a random access process on the secondary cell group. Thesecondary cell group may move to out-of-sync state, when the timealignment timer of the secondary cell group expires. To reduce the timerequired for changing the state of the secondary cell group fromout-of-state to in-sync, the wireless device may store the updatedtiming advance of the secondary cell group when the secondary cell groupbecomes out-of-sync. The stored value of the timing advance may not be aproper value of the uplink transmission timing advance when thesecondary cell group becomes in-sync again. Specially, when the wirelessdevice moves around, the propagation delay may change, for example,wireless devices may move to the coverage area of a repeater, and/or thelike. The value of the stored timing advance may be close the actualvalue of the timing advance for in-sync transmission of the wirelessdevice, especially when the cell radius is small and/or the wirelessdevice does not move, or moves slowly. In an example embodiment, thestored value of the timing advance may be employed in order to obtaintransmission timing for a random access process for a secondary cell ina secondary cell group.

According to some of the various aspects of embodiments, a wirelessdevice may be configured to communicate employing a plurality of cells.The wireless device may receive at least one control message from a basestation. The at least one control message may cause in the wirelessdevice configuration of a primary cell and at least one secondary cellin the plurality of cells and assignment of each of the at least onesecondary cell to a cell group in a plurality of cell groups (explicitlyor implicitly). The plurality of cell groups may comprise a primary cellgroup and a secondary cell group. The primary cell group may comprise afirst subset of the plurality of cells. The first subset may comprisethe primary cell. Uplink transmissions by the wireless device in theprimary cell group may employ a first synchronization signal transmittedon the primary cell as a primary timing reference. The secondary cellgroup may comprise a second subset of the at least one secondary cell.Uplink transmissions in the secondary cell group may employ a secondsynchronization signal on an activated secondary cell in the secondarycell group as a secondary timing reference.

The wireless device may receive a control command causing the wirelessdevice to transmit a random access preamble on random access resourcesof a secondary cell in the secondary cell group. The wireless device maytransmit the random access preamble on the random access resource to thebase station. Transmission timing of the random access preamble may bedetermined, at least in part, employing uplink frame and subframetransmission timing of the primary cell. The transmission timing of therandom access preamble may be determined, at least in part, furtheremploying a synchronization signal received on the secondary cell.Transmission timing of the random access preamble may be time alignedwith uplink frame and subframe transmission timing of the primary cell.

According to some of the various aspects of embodiments, the at leastone control message may comprise a plurality of random access resourceparameters. The plurality of random access resource parameters maycomprise an index, a frequency offset, and a plurality of sequenceparameters. The at least one control message may cause configuration ofthe random access resources. The wireless device may be assigned, by theconfiguration, a plurality of media access control dedicated parameterscomprising a plurality of time alignment timer values. Each timealignment timer value may be associated with a unique cell group in thewireless device.

According to some of the various aspects of embodiments, the at leastone control message may cause in the wireless device configuration of atime alignment timer for each of the plurality of cell groups. The timealignment timer may start or restart in response to the wireless devicereceiving a timing advance command to adjust a timing advance of acommanded cell group in the plurality of cell groups. The wirelessdevice may generate a first updated timing advance by updating a firsttiming advance of the secondary cell group employing at least one firsttiming advance command for the secondary cell group. The wireless devicemay store the first updated timing advance upon expiry of an associatedtime alignment timer of the secondary cell group. The wireless devicemay receive a control command causing the wireless device to transmit arandom access preamble on random access resources of a secondary cell inthe secondary cell group. The wireless device may transmit the randomaccess preamble on the random access resource to the base station. Thetransmission timing of the random access preamble may be determined, atleast in part, employing the stored first updated timing advance.

The first timing advance may be approximately (or substantially) equalto a difference between received timing of the secondary timingreference and transmission timing of the uplink signals. Approximately(substantially) equal implies that it is equal within certain accuracy,for example, within 1 micro-second, within 2 micro-seconds, or within 5micro-seconds. The accuracy may depend on wireless device timingaccuracy and/or timing advance command(s) accuracy. The first timingadvance value may be initiated by a timing advance value in a randomaccess response for a random access preamble transmitted in thesecondary cell group. The first timing advance value may be set to zerowhen the secondary cell group is configured. The stored first updatedtiming advance may be released in the wireless device when the secondarycell group is released.

According to release 10 of the LTE standard, 3GPP TS 36.213, a UE maydrop a sounding reference signal (SRS) transmission in many scenarioswhen an SRS transmission overlaps with the transmission of a PUCCH, aPUSCH, and/or a PRACH. In LTE release 10, a UE may not transmit an SRSwhenever the SRS and PUSCH transmissions happen to coincide in the samesymbol. For TDD, when one SC-FDMA symbol exists in UpPTS of a givenserving cell, the SC-FDMA symbol may be used for an SRS transmission.When two SC-FDMA symbols exist in UpPTS of a given serving cell, bothsymbols may be used for an SRS transmission and both symbols may beassigned to the same UE. A UE may not transmit a type 0 triggered SRSwhenever the type 0 triggered SRS and PUCCH format 2/2a/2b transmissionshappen to coincide in the same subframe. A UE may not transmit a type 1triggered SRS whenever the type 1 triggered SRS and PUCCH format 2a/2bor format 2 with HARQ-ACK transmissions happen to coincide in the samesubframe. A UE may not transmit a PUCCH format 2 without HARQ-ACKwhenever the type 1 triggered SRS and PUCCH format 2 without HARQ-ACKtransmissions happen to coincide in the same subframe.

In LTE release 10, a UE may not transmit an SRS whenever the SRStransmission and a PUCCH transmission carrying a HARQ-ACK and/orpositive Scheduling Request (SR) happen to coincide in the same subframeif the parameter ackNackSRS-SimultaneousTransmission is FALSE. A UE maytransmit an SRS whenever the SRS transmission and a PUCCH transmissioncarrying a HARQ-ACK and/or positive SR using a shortened format happento coincide in the same subframe if the parameterackNackSRS-SimultaneousTransmission is TRUE. A UE may not transmit anSRS whenever the SRS transmission on any serving cells and a PUCCHtransmission carrying a HARQ-ACK and/or positive SR using a normal PUCCHformat happen to coincide in the same subframe. In a UpPTS, whenever anSRS transmission instance overlaps with the PRACH region for a preambleformat 4 or exceeds the range of an uplink system bandwidth configuredin the serving cell, the UE may not transmit an SRS.

In LTE release 10, the parameter ackNackSRS-SimultaneousTransmissionprovided by higher layers may determine if a UE is configured to supportthe transmission of a HARQ-ACK on PUCCH and an SRS in one subframe. Ifthe UE is configured to support the transmission of a HARQ-ACK on aPUCCH and an SRS in one subframe, then a UE may transmit a HARQ-ACK andan SR using the shortened PUCCH format in the cell specific SRSsubframes of the primary cell where the HARQ-ACK or the SR symbolcorresponding to the SRS location is punctured. This shortened PUCCHformat may be used in a cell specific SRS subframe of the primary celleven if the UE does not transmit an SRS in that subframe. The UE may usethe normal PUCCH format 1/1a/1b or normal PUCCH format 3 for thetransmission of the HARQ-ACK and the SR. FIG. 11 summarizes exampletransmission scenarios for transmission of an SRS and a PUSCH/PUCCH inthe uplink that may be implemented in an example LTE-Advanced network(e.g. LTE release 10).

The above limitations may cause excessive dropping of SRS signals in anuplink. SRS signals may be transmitted by the UE, and may provide a basestation with information about channel conditions. Reducing the droppingpossibility of SRS signals in the uplink may enhance a base station'sability to estimate radio channel conditions. In an example scenario,the base station may need to transmit, in parallel, a combination of oneor more of the following signals: a PRACH signal, a PUCCH signal, PUSCHsignal(s), and SRS signal(s). The implementation of mechanisms employingparallel transmission of SRS and/or PRACH signals with other uplinkphysical channel signals may enhance network performance.

According to some of the aspects of some of the various embodiments, aUE may transmit an SRS signal in the same symbol in parallel withtransmission of a PUCCH and/or a PUSCH. The parallel transmission of anSRS signal and a PUCCH and/or a PUSCH may be limited to non-powerlimited scenarios wherein the UE has enough transmit power fortransmission of one or more SRSs and a PUCCH and/or PUSCH(s) during thesame subframe and/or symbol. A power limitation in a UE may be definedas a function of transmitter parameters, instantaneous transmissionpower over time, and/or maximum carrier transmit power. For example, apower limitation may cause the UE to adjust its total transmission powerto not exceed its maximum transmit power (P_(CMAX)) on any time period.For example, a UE may not exceed its maximum transmit power on anyoverlap period between different subframes of different TAGs. In anotherexample implementation, a UE may be allowed to transmit at a power abovethe limit for a short period of time (for example in a transient periodof less than 5, 10, 20, or 30 μs). Power limitations may be defined interm of transient (short term) and non-transient (long term) power.Functions such as linear averaging, log averaging, and/or the like maybe considered to define a power limited scenario. An SRS signal durationmay be one symbol. A PUCCH duration may be one subframe unless ashortened format is used. If a shortened format of a PUCCH is used, thePUCCH may not be transmitted during the last symbol of a subframe. FIG.12 is an example illustration of parallel transmission of SRS and otherphysical channel signals as per an aspect of an embodiment of thepresent invention. Other example scenarios, not shown in FIG. 12, may bealso possible. Considering that there is a timing difference betweenmultiple TAGs, the SRS transmission in a TAG may overlap with the firstsymbol of the next subframe in another TAG as shown in FIG. 12(a). Insome other scenarios, an SRS transmission in a TAG may overlap with thepenultimate symbol of the same subframe in another TAG as shown in FIG.12(b). In some other scenarios, an SRS transmission in a TAG may overlapwith the PRACH transmission as shown in FIG. 12(c).

According to some of the various aspects of embodiments, an SRS and aPUCCH and/or a PUSCH may be transmitted in the same subframe and in thesame TAG. FIG. 13 is an example illustration of parallel transmission ofan SRS and other physical channel signals as per an aspect of anembodiment of the present invention. Other example scenarios, not shownin FIG. 13, may also be possible. In an example embodiment, in anon-power limited scenario, a UE may transmit an SRS signal in onecarrier while transmitting a PUCCH and/or a PUSCH in another carrier asshown in FIG. 13(a). A PUCCH may be in a shortened format (e.g. notoccupying the last symbol of a subframe as shown in FIG. 13(b)), or maybe in a regular format (e.g. occupying the last symbol of a subframe asshown in FIG. 13(a)). In an example implementation, a PUSCH may be in ashortened format (e.g. not occupying the last symbol of a subframe), ormay be in regular format (e.g. occupying the last symbol of a subframe).In an example embodiment, a UE may transmit an SRS signal in a carrierwhile transmitting a shortened PUCCH in the same carrier.

According to some of the various aspects of embodiments, for a UE thatis not configured with multiple TAGs when the UE is scheduled by an eNBto transmit a PUSCH on the same subframe that the UE is scheduled totransmit a type 0 or a type 1 SRS, the UE may drop the SRS transmissionin that subframe. If the UE is scheduled to transmit an SRS signal and aPUCCH signal in the same subframe, the UE may drop the SRS signaltransmission except if the PUCCH transmission carrying a HARQ-ACK and/orpositive SR using a shortened format happen to coincide in the samesubframe and if the parameter ackNackSRS-SimultaneousTransmission isTRUE. If the UE is scheduled to transmit an SRS signal in parallel witha PRACH signal transmission, the UE may drop the SRS signaltransmission. In an example embodiment, the UE behavior when the UE isnot configured with multiple TAGs may be according to FIG. 11.

According to some of the various aspects of embodiments, for a UE thatis configured with multiple TAGs, a UE may transmit an SRS signal withother uplink signals if the UE is not power limited. When the UE isscheduled by the same eNB to transmit a PUSCH on the same subframe thatthe UE is scheduled to transmit a type 0 or a type 1 SRS, the UE maytransmit the SRS signal and the PUSCH signal if the PUSCH and the SRSare scheduled for transmission in different cells. In other words, theUE may transmit SRS signals in a subframe of at least one first carrierand PUSCH signals in the same subframe of at least one second carrier(e.g. where at least one first carrier and at least one second carrierdo not overlap). In another example, if the UE is scheduled to transmitan SRS signal and a regular PUCCH signal (not shortened PUCCH), the UEmay transmit both regular PUCCH and SRS signals if the SRS and the PUCCHare transmitted in different cells. In another example, if the UE isscheduled to transmit an SRS signal and a shortened PUCCH signal, the UEmay transmit both the shortened PUCCH and the SRS signals in the samecell (e.g. according to an ackNackSRS-SimultaneousTransmissionparameter) or different cells. If the UE is scheduled to transmit an SRSsignal in parallel with a PRACH signal in the same symbol and in thesame TAG, the UE may drop the SRS signal transmission. If the UE isscheduled to transmit an SRS signal in parallel with a PRACH signal inthe same symbol and in different TAGs, the UE may transmit both thePRACH and the SRS signal. Other combinations may be specified. If a UEis not configured with multiple TAGs, then the UE may not transmit anSRS and a PUSCH and/or a PUCCH in parallel. If a UE is configured withmultiple TAGs, the UE may transmit an SRS and a PUSCH and/or PUCCH inparallel in different serving cells of the same TAG or different TAGs.Please note that a shortened PUCCH and an SRS in the primary cell groupmay not be transmitted in parallel since they do not overlap in time.

In an example, user terminals (for example: UE1, and/or UE2)communicating with an eNB may be configured differently or may havedifferent sets of LTE features. For example, UE2 may be configured withmultiple timing advance groups, and UE1 may not be configured withmultiple timing advance groups. An eNB may transmit RRC messages and/orPDCCH orders to the user terminals (UE1, UE2) in unicast messages. RRCmessages and/or PDCCH orders may order (and/or configure) transmissionof type 0 and/or type 1 SRS signals for UE1 and UE2. User terminals(UE1, and/or UE2) may perform different functions in response to the RRCmessages and/or the PDCCH orders for transmission of type 0 and/or type1 SRS messages. The order (RRC or PDDCH) for transmission of type 0 ortype 1 SRS signals may be processed differently by UE1 and UE2. Forexample, in a scenario, UE1 may consider transmissions of a PUCCH and/ora PUSCH as a factor in enabling transmission of an SRS in the samesubframe as described in this disclosure. A UE1 may not transmit a PUSCHand an SRS in the same subframe. A UE2 may have more freedom intransmission of SRS signals (and drop less SRS signals), and maytransmit SRS signals simultaneous with uplink PUSCH and/or PUCCH channelsignals when UE2 is not limited in transmission power. Therefore, theRRC or PDCCH order for transmission of a type 0 and/or a type 1 SRS maybe processed differently by different UEs configured differently.

According to some of the various aspects of embodiments, if the UE isconfigured with multiple TAGs and when the UE is power limited, the UEmay drop one or more SRS signal transmissions. If one or more SRStransmissions of the wireless device in a symbol on a subframe for oneor more serving cells in a TAG overlaps with the PUCCH/PUSCHtransmission on the same or different subframe for a different servingcell in the same or another TAG, the wireless device may drop at leastone SRS when the wireless device is power limited. The UE may drop anSRS when requested by higher layers to transmit a PRACH in a secondaryserving cell in parallel with the SRS transmission in a symbol on asubframe of a different serving cell belonging to a different TAG if theUE is power limited.

According to some of the various aspects of embodiments, the UE may dropan SRS, a PUSCH, and/or a PUCCH signal when requested by higher layersto transmit a PRACH in a serving cell in parallel with the SRS, PUSCH,and/or PUCCH in the same cell group. The UE may transmit an SRS, aPUSCH, and/or a PUCCH signal in parallel with transmission of a PRACH ina serving cell if the PRACH is transmitted in a different cell groupcompared with the SRS, the PUSCH, and/or the PUCCH signal. For example,when a UE transmits a PRACH signal in a subframe of a secondary cell ofa secondary TAG, the UE may drop the SRS, and/or the PUSCH in the samesubframes of the serving cells belonging to the secondary TAG. When a UEtransmits a PRACH signal in a subframe of a secondary cell of asecondary TAG, the UE may also transmit an SRS, and/or a PUSCH in thesame subframes of the serving cells belonging to TAGs different from thesecondary TAG.

According to some of the various aspects of embodiments, when multipletiming advance groups are configured and in a non-power-limitedscenario, a UE may allow parallel transmission of SRS and PUSCH and/orPUCCH signals in the same subframe of different TAGs and/or the sameTAGs. When a UE is not power limited, the UE may not drop the SRS in aTAG when the PUCCH/PUSCH are transmitted in the same subframe in anotherTAG or in another carrier of the same TAG. A PUCCH may be in a shortenedformat (e.g. not occupying the last symbol of a subframe), or may be ina regular format (e.g. occupying the last symbol of a subframe). When aPUCCH with a shortened format is transmitted in a subframe of a carrier,an SRS may be transmitted on the same subframe of the carrier. Accordingto some of the various aspects of embodiments, when multiple timingadvance groups are configured, parallel SRS transmission with otherphysical layer channel signals may be allowed.

When an SRS and a PUCCH, a PUSCH, and/or a PRACH are transmitted ondifferent cells, then the UE transmitter may map a channel signal on theresource elements of the corresponding cell, and there may be noresource element overlap between an SRS and other channel signals sincesignals are transmitted on radio resource of different cells. Thisimplementation may be enabled by a digital signal processor thatprocesses signals for transmission on multiple cells. The disclosedimplementation may increase UE performance and may reduce thepossibility of dropping SRS signal(s). Example implementations fortransmission of SRS signals, PUCCH signals, PUSCH signals, and PRACHsignals are described in this specification.

According to some of the various aspects of embodiments, for a UE nothaving a first capability when the UE is scheduled by an eNB to transmita PUSCH on the same subframe that the UE is scheduled to transmit a type0 or type 1 SRS, the UE may drop the SRS transmission in that subframe.If the UE is scheduled to transmit an SRS signal and a PUCCH signal inthe same subframe, the UE may drop the SRS signal transmission except ifthe PUCCH transmission carrying a HARQ-ACK and/or a positive SR using ashortened format happen to coincide in the same subframe and if theparameter ackNackSRS-SimultaneousTransmission is TRUE. If the UE isscheduled to transmit an SRS signal in parallel with a PRACH signaltransmission, the UE may drop the SRS signal transmission. In an exampleembodiment, the UE behavior when the UE is not configured with multipleTAGs may be according to FIG. 11.

According to some of the various aspects of embodiments for a UE havinga first capability, the UE may transmit an SRS signal with other uplinksignals if the UE is not power limited. When the UE is scheduled by thesame eNB to transmit a PUSCH on the same subframe that the UE isscheduled to transmit a type 0 or a type 1 SRS, the UE may transmit theSRS signal and the PUSCH signal if the PUSCH and the SRS are scheduledfor transmission in different cells. In other words, the UE may transmitSRS signals in a subframe of at least one first carrier and PUSCHsignals in the same subframe of at least one second carrier (e.g when atleast one first carrier and at least one second carrier do not overlap).In another example, if the UE is scheduled to transmit an SRS signal anda regular PUCCH signal (e.g not a shortened PUCCH), the UE may transmitboth a regular PUCCH and SRS signals if the SRS and the PUCCH aretransmitted in different cells. In another example, if the UE isscheduled to transmit an SRS signal and a shortened PUCCH signal, the UEmay transmit both the shortened PUCCH and SRS signals in the same cell(e.g. according to an ackNackSRS-SimultaneousTransmission parameter) ordifferent cells. If the UE is scheduled to transmit an SRS signal inparallel with a PRACH signal in the same symbol and in the same TAG, theUE may drop the SRS signal transmission. If the UE is scheduled totransmit an SRS signal in parallel with a PRACH signal in the samesymbol and in different TAGs, the UE may transmit both the PRACH and theSRS signal transmission. Other combinations may be specified.

If a UE does not have the first capability, then the UE may not transmitan SRS and a PUSCH/PUCCH in parallel. If the UE has the firstcapability, the UE may transmit an SRS and a PUSCH/PUCCH in parallel indifferent serving cells of the same TAG or different TAGs. The firstcapability, for example, may be: a capability of supporting multiple TAGconfigurations; a capability of parallel SRS transmissions; a capabilityof supporting specific releases of an LTE standard; a capability of atransmission combination; a combination thereof, and/or the like. In anexample implementation, the first capability may be communicated to thebase station implicitly or explicitly using one or more parameters in anRRC radio capability message. The first capability may be implicitlydetermined according to the features or other capability of the wirelessdevice. For example, a UE transmitting a radio capability message to abase station that indicates that the UE supports multiple TAGconfiguration may have the first capability.

In an example, user terminals (e.g. UE1, and/or UE2) communicating withan eNB may have different sets of capabilities or may have differentsets of LTE features. For example, UE2 may be capable of supportingconfigurations of multiple timing advance groups, and UE1 may not becapable of supporting configurations of multiple timing advance groups.An eNB may transmit an RRC messages and/or PDCCH orders to the userterminals (e.g. UE1, and/or UE2) in unicast messages. RRC messagesand/or PDCCH orders may order (and/or configure) transmission of type 0and/or type 1 SRS signals for UE1 and UE2. The user terminals (e.g. UE1,and/or UE2) may perform different functions in response to the RRCmessages and/or the PDCCH orders for transmission of type 0 and/or type1 SRS messages. The order (RRC or PDDCH) for transmission of type 0 ortype 1 SRS signals may be processed differently by UE1 and UE2. Forexample, in a scenario, UE1 may consider transmissions of PUCCH and/orPUSCH signals as a factor in enabling transmission of an SRS in the samesubframe as described in this disclosure. UE1 may not transmit a PUSCHand an SRS in the same subframe. UE2 may have more freedom intransmission of SRS signals (and drop less SRS signals) and may transmitSRS signals simultaneous with uplink PUSCH and/or PUCCH channel signalswhen UE2 is not limited in transmission power. Therefore, the RRC orPDCCH order for transmission of type 0 and/or type 1 SRS signals may beprocessed differently by different UEs configured differently.

According to some of the various aspects of embodiments, a wirelessdevice may receive at least one radio resource control message from abase station. The at least one radio resource control message may beconfigured to cause in the wireless device configuration of a primarycell and at least one secondary cell in a plurality of cells. The atleast one radio resource control message may be configured to cause inthe wireless device configuration of transmissions of sounding referencesignals by the wireless device. The transmission of sounding referencesignal may be triggered by one of the RRC messages or one or more PDCCHorders. A sounding reference signal (SRS) may be configured to betransmitted in the last symbol of a first subframe on a first cell inthe plurality of cells. An SRS configured for transmission may betransmitted or dropped depending on other parallel transmissions by thewireless device. Transmission of the sounding reference signal may betriggered by receiving one or more PDCCH packets or one or more of theat least one radio resource control message. The configuration of thesounding reference signal may indicate a transmission period of soundingreference signals.

In one example embodiment, we consider parallel transmission of PUCCHand/or PUSCH signals/packets with the SRS transmission and no randomaccess preamble may be transmitted in the last symbol in parallel othersignals. The wireless device may transmit at least one packet on atleast one second cell in the plurality of cells in a plurality ofsymbols of the first subframe. The plurality of symbols may comprise thelast symbol of the first subframe. The wireless device may transmit thesounding reference signal if the following conditions are satisfied: theat least one radio resource control message further causes in thewireless device configuration of a plurality of cell groups; thewireless device has sufficient power to transmit the sounding referencesignal and the at least one packet; and the first cell is different fromthe at least one second cell. The wireless device may drop the soundingreference signal in the last symbol if the wireless device is notconfigured with a plurality of cell groups. In this example embodiment,parallel transmission of SRS with other signals may be supported whenmultiple TAGs are configured. If UE is not configured with multipleTAGs, then SRS and PUSCH/PUCCH may not be transmitted in parallel. If UEis configured with multiple TAGs, then SRS and PUSCH/PUCCH may betransmitted in parallel from different serving cells of the same TAG ordifferent TAGs. The rule may be extended to a scenario when multipleSRSs are configured for transmission. Each of the SRS signals may followthe example rule. The power limitations may apply to SRS signals thatmay be transmitted when UE has sufficient power. For example, a UE maydrop all SRS signals when UE does not have sufficient power to transmitall of them in the last symbol. Or a UE may drop a first subset of SRSsignals, and transmit a second subset of SRS signals if UE hassufficient power to transmit the second subset of SRS signals inparallel with other signals. A packet in the at least one packet is atleast one of the following: a physical uplink control channel packet;and a physical uplink shared channel packet.

According to some of the various aspects of embodiments, thetransmission rule may be extended for the case when a random accesspreamble is scheduled for transmission in symbols comprising the lastsymbol. When a random access preamble is transmitted in symbols of acell of a TAG, no other signal may be transmitted in the same TAG inparallel with the random access preamble. The wireless device may dropthe sounding reference signal in the last symbol if: the at least oneradio resource control message further causes in the wireless deviceconfiguration of a plurality of cell groups; the wireless device hassufficient power to transmit both the sounding reference signal and theat least one packet; and a random access preamble is transmitted onsymbols comprising the last symbol on a cell in a cell group comprisingthe first cell.

In an example embodiment, the wireless device may drop the soundingreference signal in the last symbol if: the at least one radio resourcecontrol message further causes in the wireless device configuration of aplurality of cell groups; and the wireless device has insufficient powerto transmit both the sounding reference signal and the at least onepacket. As discussed the rule may be extended to multiple soundingreference signals. The wireless device may give a transmission power ofthe sounding reference signal a lower priority compared with a priorityof a transmission power of a random access preamble; and a priority of atransmission power of the at least one packet.

The wireless device may drop the sounding reference signal in the lastsymbol if: the at least one radio resource control message furthercauses in the wireless device configuration of a plurality of cellgroups; the wireless device has sufficient power to transmit both thesounding reference signal and the at least one packet; and the firstcell is in the at least one second cell.

According to some of the various aspects of embodiments, the at leastone radio resource control message may further cause in the wirelessdevice, assignment of each of the at least one secondary cell to onecell group in the plurality of cell groups if the at least one radioresource control message further causes in the wireless deviceconfiguration of a plurality of cell groups. A cell group in theplurality of cell groups may comprise a subset of the plurality ofcells. Uplink transmissions of the wireless device in the cell group mayemploy a synchronization signal on an activated cell in the cell groupas a timing reference.

According to some of the various aspects of embodiments, the wirelessdevice may receive at least one radio resource control message from abase station. The at least one radio resource control message may beconfigured to cause in the wireless device configuration of: a primarycell and at least one secondary cell in a plurality of cells; andtransmissions of sounding reference signals by the wireless device. Asounding reference signal may be configured to be transmitted on thelast symbol in a first subframe on a first cell in the plurality ofcells. An SRS configured for transmission may be transmitted or droppeddepending on other parallel transmissions by the wireless device.Transmission of the sounding reference signal may be triggered byreceiving one or more PDCCH packets or one or more of the at least oneradio resource control message. The configuration of the soundingreference signal indicates a transmission period of sounding referencesignals. A scenario is considered in which no random access preamble isconfigured for transmission in parallel with the last symbol of thefirst subframe.

The wireless device may transmit at least one packet on at least onesecond cell in the plurality of cells in a plurality of symbols of thefirst subframe. The plurality of symbols may comprise the last symbol ofthe first subframe. The wireless device may transmit the soundingreference signal if the following conditions are satisfied: the wirelessdevice supports configuration of a plurality of cell groups; thewireless device has sufficient power to transmit the sounding referencesignal and the at least one packet; and the first cell is different fromthe at least one second cell. The wireless device may drop the soundingreference signal in the last symbol if the wireless device does notsupport configuration of a plurality of cell groups.

In an example embodiment, the wireless device may drop the soundingreference signal in the last symbol if: the wireless device supportsconfiguration of a plurality of cell groups; and the wireless device hasinsufficient power to transmit both the sounding reference signal andthe at least one packet. As described in the specification, the rule maybe extended to a scenario wherein many SRSs are configured fortransmission in the last symbol. In an example embodiment, the wirelessdevice may drop the sounding reference signal in the last symbol if: thewireless device supports configuration of a plurality of cell groups;the wireless device has sufficient power to transmit both the soundingreference signal and the at least one packet; and the first cell is inthe at least one second cell. The wireless device may drop the soundingreference signal in the last symbol if: the wireless device supportsconfiguration of a plurality of cell groups; the wireless device hassufficient power to transmit both the sounding reference signal and theat least one packet; and a random access preamble is transmitted insymbols comprising the last symbol on a cell in a cell group comprisingthe first cell. When no cell groups are configured, then all cellsbelong to the same primary cell group.

According to some of the various embodiments, when a UE is powerlimited, parallel transmission of SRS and PUCCH, PUSCH and/or PRACHsignals may not be possible. One or some of the SRS, PUCCH, PUSCH and/orPRACH transmissions may be dropped or the transmit power of one or someof the SRS, PUCCH, PUSCH and/or PRACH transmissions may be reduced toaddress the limitations in the transmit power. There may be a need todefine rules for parallel transmission of SRS, PUCCH, PUSCH and/or PRACHsignals when a UE is power limited. Otherwise, the UE may exceed itstransmission power or perform an unexpected behavior. There may be manydifferent scenarios for such a parallel transmission, and a givenscenario may require its own solution. Some examples of paralleltransmission scenarios are listed below: s SRS+PRACH; s SRS+PUCCH; sSRS+k PUSCH; s SRS+PRACH+PUCCH; s SRS+PRACH+k PUSCH; s SRS+PUCCH+kPUSCH; and s SRS+PRACH+PUCCH+k PUSCH.

According to some of the various embodiments, PUSCH and PRACHtransmissions may be given a higher priority compared with SRStransmissions. Therefore, whenever a UE is power limited and an SRSconfiguration indicates parallel transmission of SRS(s) with PUSCH andor PRACH signals, some of the SRS transmissions may be dropped.

If a UE does not have enough power for transmission of s SRS, PRACH, andPUSCH signals; then PRACH and PUSCH signal transmissions may take higherpriority over SRS signal transmission. In one example implementation, ifa UE does not have enough power for simultaneous transmission, then theUE may not transmit any SRS signal and may drop the SRS transmission.This approach may be simple to implement, but may result in excessiveSRS droppings. In a second example embodiment, if UE does not haveenough power for parallel transmission of SRS(s) and other signals, thenthe UE may transmit s1 SRS signals on s1 cells, wherein s1 is smallerthan s. s1 cells may be selected for SRS signal transmission from scells. s1 SRS signals may be transmitted assuming that the UE hassufficient power to transmit s1 SRS signals in parallel with othersignals (e.g. PUCCH, PUSCH, and/or PRACH signals). The selection of s1cells among s cells for SRS transmission may be according to apredetermined rule. The predetermined rule may be, for example: s1 cellswith smaller cell index; cells belonging to sTAG with smaller cellindex; cells requiring lower power to transmit SRS; cells requiringhigher power to transmit SRS and/or any other predetermined rule in theUE. The UE may drop s2 SRS signals and transmit s1 SRS signals in thesame symbol. In this mechanism, some SRS signal(s) may be dropped. Whena UE does not have sufficient power to transmit s SRS signals inparallel with other packets, the UE may at least transmit some of theSRS signals while dropping some others in the same symbol. The mechanismmay be more efficient than dropping all the SRS signals in the UE whenthe UE is power limited during SRS transmission. This mechanism could beapplied to intra-frame overlap (in the same or different TAGs) as wellas inter-frame overlap of SRS signals in different TAGs. Reducing SRSdropping may increase spectral efficiency, since a base station may havemore information about channel conditions when the base station receivesmore SRS signals from UEs. This mechanism is superior to othertechniques, wherein a UE drops all parallel SRS transmissions in asymbol when UE is power limited in the symbol. If PRACH, PUCCH and/or kPUSCH signals are transmitted in parallel and their total transmit powerexceeds {circumflex over (P)}_(CMAX)(i) then, all overlapping SRS signaltransmissions may be dropped.

According to some of the various aspects of embodiments, to determinethe priority of SRS transmission when a PUCCH is transmitted, thefollowing scenarios may be considered: s SRS+PUCCH; s SRS+PUCCH+PRACH; sSRS+PUCCH+k PUSCH; and s SRS+PUCCH+PRACH+k PUSCH.

According to some of the various aspects of embodiments, if a shortenedversion of a PUCCH signal is used, transmission of an SRS signal and aPUCCH signal may not overlap. In one example embodiment, a PUCCHtransmission may take a higher priority than an SRS transmission.Therefore, in power scaling (or power reduction, or signal dropping)rules, the following priorities may be considered: PRACH>PUCCH>PUSCHwith UCI>PUSCH>SRS.

If a UE does not have enough power for transmission of s SRS, a PRACH,PUCCH and PUSCH signals, then PRACH, PUCCH and PUSCH transmissions maytake priority over SRS signal transmissions. In one exampleimplementation, if a UE does not have enough power for simultaneoustransmission, then the UE may not transmit any SRS signal and may dropSRS transmissions.

When multiple TAGs are configured in an LTE release 11 or abovecompliant UE, and when SRS transmission is scheduled in parallel with aPUCCH transmission, the SRS transmission may be dropped when there is afull overlap and/or partial overlap in transmission time. In thisembodiment, the SRS transmission mechanism of first UEs may be differentwith the SRS transmission of second UEs. First UEs may supportmultiple-TAG capability and second UEs may not support multiple-TAGcapability. First UEs may be configured with multiple TAGs and secondUEs may not be configured with multiple TAGs.

According to some of the various embodiments, the UEs may not transmitPUCCH format 2 signals without a HARQ-ACK whenever a type 1 triggeredSRS and PUCCH format 2 without HARQ-ACK transmissions happen to coincidein the same subframe. In this embodiment, UEs may drop SRS transmissionwhen an SRS transmission would collide with a PUCCH transmission whenthere is an overlap between different TAGs and the UE does not havesufficient power.

In another example embodiment, a different rule may be adopted. If a UEconfigured with multiple TAGs does not have enough power fortransmission of s SRS, PRACH, PUCCH and PUSCH signals, then transmissionof PUCCH signals may take a higher priority than an SRS signal. Anexception exists in at least the following scenario in which SRStransmission priority may be higher than PUCCH transmission priority:PUCCH Format A=PUCCH format 2 without HARQ-ACK transmissions; SRS FormatB=Type 1 triggered SRS.

PUCCH Format A transmission may take a lower priority than SRS Format Btransmission. Therefore, when Type 1 triggered SRS and PUCCH format 2without HARQ-ACK transmission coincide and the UE is power limited, theUE may drop PUCCH signal transmission and may transmit Type 1 triggeredSRS. In an example, the priorities may be defined according to thefollowing: PRACH>PUCCH (except PUCCH Format A)>PUSCH with UCI>PUSCH>Type1 triggered SRS>PUCCH Format A>Type 0 Triggered SRS.

In another example embodiment, an SRS signal may be dropped if there isnot enough power according to priorities assigned to channels. Themechanisms may be triggered if there is an inter-frame overlap betweenSRS and other signals.

According to some of the various embodiments, a wireless device mayreceive at least one radio resource control message from a base station.The at least one radio resource control message may be configured tocause in the wireless device configuration of transmissions of soundingreference signals by the wireless device. n sounding reference signalsare configured to be transmitted in a first subframe, n being greaterthan 1. Each sounding reference signal is configured for transmission ona different cell from other sounding reference signals. The wirelessdevice may transmit at least one packet on at least one first cell inthe plurality of cells in a plurality of symbols of the first subframe.The plurality of symbols may comprise the last symbol of the firstsubframe. The wireless device may transmit a k subset of the n soundingreference signals in the last symbol, wherein 1<=k<n. The k subset ofSRSs are transmitted on k cell(s). The wireless device may drop an msubset of the n sounding reference signals in the last symbol, wherein1<=m<n.

The wireless device has sufficient power to transmit in parallel boththe k subset of the n sounding reference signals and the at least onepacket. The wireless device has insufficient power to transmit inparallel the k subset of the n sounding reference signals, the m subsetof the n sounding reference signals, and the at least one packet. Thewireless device may drop one or more of the sounding reference signals,but the wireless device may drop one or more sounding reference signalsbecause it is power limited.

In an example embodiment, if UE has enough power for transmission of sSRS signal and preamble transmission on an SCell, UE may transmit SRSsignal on s uplink carriers. If UE does not have enough power fortransmission of s SRS signal and preamble, then preamble transmissionmay take priority over SRS signal transmission. Three implementationexamples are provided. In one example implementation, if UE does nothave enough power for simultaneous transmission of preamble and s SRSsignals, then UE may not transmit any SRS signal and may transmit thepreamble. In a second example embodiment, if UE does not have enoughpower for simultaneous transmission of preamble and s SRS signals, thenUE may transmit preamble and s1 SRS signals on s1 cells, wherein s1 issmaller than s. S1 cells may be selected for SRS signal transmissionfrom s cells. The selection of s1 cells among s cells for SRStransmission, may be according to a predetermined rule. Thepredetermined rule may be such as: s1 cells with smaller cell index, orcells belonging to sTAG with smaller cell index, or any otherpredetermined rule in the UE. In a third example embodiment, powerscaling may be used for transmission of s SRS signals. SRS signal powermay be scaled down, so that transmission of s SRS signal and preamblesignal do not exceed UE allowed transmission power. If the totaltransmit power of the UE for the Sounding Reference Symbol would exceed{circumflex over (P)}_(CMAX)(i), the UE may scale {circumflex over(P)}_(SRS,c)(i) for the serving cell c in subframe i such that thecondition

${\sum\limits_{c}\;{{w(i)} \cdot {{\hat{P}}_{{SRS},c}(i)}}} \leq \left( {{{\hat{P}}_{CMAX}(i)} - {{\hat{P}}_{PRACH}(i)}} \right)$

is satisfied where {circumflex over (P)}_(SRS,c)(i) is the linear valueof P_(SRS,c)(i), {circumflex over (P)}_(CMAX)(i) is the linear value ofP_(CMAX) defined in subframe i and w(i) is a scaling factor of{circumflex over (P)}_(SRS,c)(i) for serving cell c where 0<w(i)≤1.Other functions in addition to linear value may be supported. Forexample, average power, and/or the like. In an example, w(i) values maybe the same across serving cells, in which w(i) is not zero.

The wireless device may also drop some of the SRS signal(s) for otherreasons. The wireless device may drop a sounding reference signal in then sounding reference signals if: the wireless device has sufficientpower to transmit both the sounding reference signal and the at leastone packet; and the sounding reference signal is configured to betransmitted on a cell in the at least one first cell. The wirelessdevice may drop the sounding reference signal in the last symbol if: thewireless device has sufficient power to transmit both the soundingreference signal and the at least one packet; and the sounding referencesignal is configured to be transmitted on a cell in parallel with arandom access preamble transmitted on the cell or another cell in thesame cell group.

Transmission of the sounding reference signal may be triggered byreceiving a PDCCH packet or one or more of the at least one first radioresource control message. The configuration of the sounding referencesignal may indicate a transmission period of the sounding referencesignals. The wireless device may give a transmission power of thesounding reference signal a lower priority compared with: a priority ofa transmission power of a random access preamble; and a priority of atransmission power of the at least one packet. A packet in the at leastone packet is at least one of the following: a physical uplink controlchannel packet; and a physical uplink shared channel packet.

The at least one radio resource control message may be configured tocause in the wireless device configuration of a primary cell and atleast one secondary cell in a plurality of cells. The at least one radioresource control message may be configured to cause in the wirelessdevice assignment of each of the at least one secondary cell to a cellgroup in a plurality of cell groups. The plurality of cell groups maycomprise a primary cell group and a secondary cell group. The primarycell group may comprise a first subset of the plurality of cells. Thefirst subset may comprise the primary cell. The secondary cell group maycomprise a second subset of the at least one secondary cell.

According to some of the various embodiments, within transition periods(overlap periods) where one carrier is transmitting subframe n butanother carrier has already begun transmitting subframe n+1, terminalpower limitations may arise. Even though the scheduling assignments maynot lead to any power limitation during the periods where carrierstransmit the same subframe, power may not be sufficient in thetransition periods if one cell increases its requested power but anothercell has not yet started transmitting the next subframe. FIG. 14 is anillustration of power limitations during a timing overlap period betweendifferent subframes from different TAGs as per an aspect of anembodiment of the present invention. The sum of the power of subframe nin TAG1 and the power of subframe n+1 in TAG2 may be more than themaximum allowed transmission power of the wireless device. In FIG. 14,power levels for subframes are shown to be fixed for simplicity. Duringthe transient period, for example at the two ends of each subframe,transmission power may change. For example, if a subframe duration is 1msec and a transient period duration is 20 micro-seconds, then thetransmit power may be substantially fixed during the subframe, exceptduring the transient period where the power may change. In anotherexample embodiment, transient periods may also be defined at slotboundaries near or at the middle of a subframe.

FIG. 15 is an illustration of power limitations during a timing overlapbetween an SRS signal and a PUCCH and/or PUSCH signal as per an aspectof an embodiment. The overlap between PUCCH and/or PUSCH transmissionand SRS transmission from other TAGs may be in the range of, forexample, one micro-second to tens of micro-seconds. A rule may bedefined for parallel transmission of PUCCH and/or PUSCH and SRS signalswhen there is an overlap between an SRS transmission in one TAG andPUSCH/PUCCH transmissions in another TAG. According to some of thevarious aspects of embodiments, PUCCH and/or PUSCH signal transmissionsmay be assigned a higher priority compared with SRS signaltransmissions. The example is shown for two TAGs and two cells, butother similar examples may be provided with more than two TAGs and/orone or more cells in each TAG. The rules provided here may begeneralized to cover those scenarios.

A UE may support parallel transmission of SRS with other signals, forexample, PUCCH, PUSCH, and/or PRACH according to certain transmissionrules. For example, a UE configured with multiple TAGs, or a UE withcapability of multiple TAG configurations may support paralleltransmission of SRS with other signals. Some other UEs, for example, UEssupporting release 10 or lower may not support parallel transmission ofSRS with other signals. We focus our discussion here on UEs that havethe capability of transmitting SRS with other signals according tocertain transmission rules.

If the SRS transmission of the wireless device in a symbol on subframe nfor a given serving cell in a TAG overlaps with the PUCCH/PUSCHtransmission on subframe n or subframe n+1 for another serving cell inthe same or another TAG, the wireless device may drop SRS if its totaltransmission power exceeds the maximum allowable transmission power onany overlapping period of the symbol. This rule may be generalizedcovering scenarios with multiple cell SRS transmissions and multiplecell PUSCH and/or PUCCH transmissions. If the SRS transmission of thewireless device in a symbol on subframe n for a given serving celloverlaps with the SRS transmission on subframe n on other servingcell(s) and with PUSCH/PUCCH transmission on subframe n or subframe n+1for another serving cell(s) the wireless device may drop the SRStransmissions if the total transmission power exceeds the maximumallowable transmission power on any overlapping period of the symbol.

If the transmission overlap between PUCCH and/or PUSCH(s) and SRSsignals is below a second time period, during the overlap the power maybe below the UE maximum allowed transmission power even if sum of SRSsymbol and PUCCH/PUSCH subframe transmission power may exceed the UEmaximum allowed transmission power. During the transient period, the UEmay reduce its transmission power to a lower level compared with thetransmission power during the non-transient period of a symbol or asubframe. In this case, even though SRS and PUCCH/PUSCH transmissionpower may exceed the UE maximum allowed transmission power, the UE maynot drop the SRS signal and may transmit both SRS signal and PUSCHsignals. As described before this may be applied when more than one celltransmit SRS signal and more than one cell transmits PUCCH and/or PUSCH.

If the transmission overlap between PUCCH and/or PUSCH and SRS signalsis relatively large, then the SRS signals may be dropped if sum of SRSsymbol power and PUCCH/PUSCH subframe transmission power exceeds the UEmaximum allowed transmission power. In an example implementation, if sumof SRS symbol power and PUCCH/PUSCH subframe transmission power exceedsthe UE maximum allowed transmission power and overlap between PUCCHand/or PUSCH and SRS signals exceeds a first period, the SRS may bedropped. In an example implementation, if sum of SRS symbol power andPUCCH/PUSCH subframe transmission power exceeds the UE maximum allowedtransmission power and overlap between PUCCH and/or PUSCH and SRSsignals is below a second period, the SRS may be transmitted. The secondperiod may be below the transient period. The UE may reduce transmissionpower of SRS and/or PUCCH/PUSCH signals during the transient period toovercome power limitations, and the UE may not drop the SRS signal. Theprocess of using reduced power during transient periods to reduce SRSdropping may increase spectral efficiency. The more base stationreceives SRS signals, the better it may estimate wireless channelcharacteristics. The UE may not restrict itself in calculating totaltransmission power by summing SRS symbol power and PUSCH/PUCCH subframepower whenever there is an overlap of any size. The UE may takeadvantage of reduced power during transient period to ensure the totalpower is below the maximum power during any period of time, whilesummation of SRS symbol power and PUSCH/PUCCH subframe power may exceedthe power limit

A UE receiver may cope with a relative propagation delay difference upto a certain limit, for example 30 μs, among the component carriers tobe aggregated (e.g. in inter-band non-contiguous CA). The base stationtime alignment may be up to a certain limit, for example 1.3 μs. In anexample, a UE may cope with a delay spread of up to 31.3 μs among thecomponent carriers monitored at the receiver.

In this solution, an SRS dropping operation may be applied to SRSsignals when the TAG timing difference is relatively large and the UEcannot ensure power constraints by adjusting transient periodtransmission power. The power constraint is that the total transmissionpower should not exceed the maximum allowable transmission power on anyoverlapping period of the symbol.

In examples presented in FIG. 15(a) and FIG. 15(b), a sum of SRS symbolpower in subframe n and subframe PUSCH/PUCCH power in subframe n+1 mayexceed the maximum allowable transmission power. An SRS signal may bedropped in FIG. 15(a). The UE may not be able to comply with powerconstraints when the overlap period is larger than a first period. Forexample, the overlap period in FIG. 15(a) may be 25 micro-seconds ormore. The UE may drop SRS signal in FIG. 15(a). The UE may transmit SRSsignal in FIG. 15(b). The UE may comply with power requirements byreducing SRS and/or PUSCH/PUCCH during the transient period. The partialoverlap in FIG. 15(b) may be below a second period.

FIG. 16 provides a more detailed illustration of FIG. 15. In FIG. 16(a),UE may drop SRS signal. UE may exceed its transmission power even thoughit may reduce its power during the transient period. In FIG. 16(b) UEmay transmit SRS in subframe n in TAG1 and PUCCH/PUSCH in subframe n+1in TAG2, even though the sum of SRS symbol power and PUCCH/PUSCH powerexceeds UE total power. UE may comply with power requirements byreducing its power during the transient period. Other examples may beprovided with different power levels and overlap periods.

To test an example operation as described in FIG. 15 and FIG. 16, a testset up may be implemented, in which the TAG timing difference (oroverlapping period) is increased from a small period to a large period.The UE may be configured to transmit SRS on TAG1 and PUSCH/PUCCH onTAG2. The UE may be put in a power limited condition (e.g. by increasingthe attenuation of the channel pathloss). As the TAG timing differenceincreases the probability of SRS dropping may also increase. For smallTAG timing difference, UE may comply with power requirements by reducingtransient period power. For a large TAG timing difference, a UE may dropSRS signals more often to comply with power requirements. If basestation scheduling operation can be configured, the test plan may alsoconsider designing packet scheduling with SRS transmission to betterdetermine the operation of the disclosed mechanisms.

When SRS symbol power and PUCCH/PUSCH subframe power are considered forpower calculations, the SRS signal may be dropped or reduced even if thepartial overlap is small compared with symbol duration. This operationmay require a simple process in the UE, but may increase SRS dropping inthe system. When the first period is above zero, for example 1, 5, 10,30 or more micro seconds, the SRS dropping possibility may decrease. Thefirst period (as well as the second period) may not be a fixed period,and depending on UE configuration, position, power requirements, channelbehavior, the first period may change. In another example, the thresholdmay be in the range of a cyclic prefix of a symbol. In urbandeployments, for example when a cell radius is small and in scenarioswherein TAG timing difference is small compared with transient period,SRS dropping may be reduced by reducing the power in the transientperiod. When there is an overlap above a period between SRS and PUCCHand/or PUSCH transmissions and the SRS symbol power and PUCCH/PUSCH maybecome an important factor in total power calculations, and the SRSsignal may be dropped. The reduction of power during transient periodmay reduce the possibility of SRS dropping and increase systemefficiency. An eNB may employ SRS signals for channel estimation, andreduction of the SRS dropping (or power reduction) may increase eNB airinterface efficiency. In an example embodiment, power reduction duringthe transient period may not always eliminate SRS dropping because ofinter-frame overlap power limitations, but it may reduce the possibly ofSRS dropping when the overlap period is relatively small.

The same mechanism may be applied to a scenario, wherein SRS(s) aretransmitted in parallel with a PRACH signal. The sum of SRS, PRACH,and/PUCCH/PUSCH power may exceed maximum allowed power. The wirelessdevice may transmit PRACH in a secondary serving cell in parallel withSRS transmission in a symbol on a subframe of a different serving cellbelonging to a different TAG. The wireless device may drop an SRS if thetotal transmission power exceeds the maximum allowed limit on anyoverlapped period in the symbol. When the overlap period is small (forexample compared with the transient period), the UE may reducetransmission power during the transient period and may transmit SRS, andPRACH and reduce the possibility of SRS dropping.

According to some of the various embodiments, a wireless device mayreceive at least one radio resource control message from a base station.The at least one radio resource control message may cause in thewireless device configuration of a plurality of cells comprising aprimary cell and at least one secondary cell and assignment of each ofthe at least one secondary cell to a cell group in a plurality of cellgroups. The at least one radio resource control message may cause in thewireless device configuration of transmissions of sounding referencesignals by the wireless device. Each of the plurality of cell groups maycomprise a subset of the plurality of cells.

The wireless device may decode an information element in a receivedcontrol message indicating transmission of one of the sounding referencesignals in a symbol on subframe n on a first cell in a first cell groupin the plurality of cell groups. The information element may be in oneof the following: the at least one radio resource control message; and aphysical downlink control channel packet. The symbol may overlap in timewith transmission of an uplink packet on at least one of: subframe n ina second cell, the second cell in a second cell group in the pluralityof cell groups; and subframe n+1 in the second cell. The first cellgroup may be different from the second cell group.

The wireless device may transmit the one of the sounding referencesignals if a power parameter is less than a maximum allowabletransmission power in the symbol. A calculation of the power parametermay consider transmission power of the uplink packet if the overlappingin time exceeds a first duration. SRS symbol power may have a lowerpower priority compared with PUCCH and/or PUSCH signal powers. In anexample embodiment, the overlapping period may be more than thetransient period (e.g. twenty micro seconds). If the overlap is smallerthan the first period, the wireless device may or may not considertransmission power of the uplink packet depending on many factors. Forexample, if the wireless device is able to avoid SRS dropping byreducing the transmission power during the transient period, thewireless device may not consider transmission power of the uplink packetin power calculations. The transmission power of uplink packet refers tosubframe transmission power.

The calculated power parameter may a total transmission power of thewireless device. The wireless device may determine the first durationsuch that the total transmission power is less than or equal to themaximum allowable transmission power of the wireless device during theoverlapping in time.

The wireless device may limit the total transmission power to themaximum allowable transmission power of the wireless device during theoverlapping in time. The wireless device may transmit a reducedtransient transmission power (compared with subframe power) of at leastone of the uplink packet and the sounding reference signal during theoverlapping in time. The overlap in time may be less than the firstduration.

The wireless device may drop the one of the sounding reference signalsif the calculated power parameter is greater than the maximum allowabletransmission power in the symbol. The calculation may ignoretransmission power of the uplink packet if the overlapping in time issmaller than a second duration. The wireless device may transmit SRSsignal even though the sum of SRS symbol signal and PUCCH/PUSCH (uplinkpacket(s)) subframe transmission power exceeds the maximum allowabletransmission power, if the overlapping in time is smaller than a secondduration. The wireless device may comply with the power requirementsconsidering that the transient power is smaller than the symbol orsubframe power. The second duration may be less than or equal to thefirst duration. The uplink packet is transmitted on one of a physicaluplink control channel; and a physical uplink shared channel. Thewireless device may reduce a transient transmission power (compared withsubframe and/or symbol transmission power) of at least one of the uplinkpacket and the sounding reference signal during the overlapping in time.The overlapping in time may be less than the second duration.

According to some of the various embodiments, within transition periods(overlap periods) where one carrier is transmitting subframe n butanother carrier has already begun transmitting subframe n+1, terminalpower limitations may arise. Even though the scheduling assignments maynot lead to any power limitation during the periods where carrierstransmit the same subframe, power may not be sufficient in thetransition periods if one cell increases its requested power but anothercell has not yet started transmitting the next subframe. FIG. 14 is anillustration of power limitations during a timing overlap period betweendifferent subframes from different TAGs as per an aspect of anembodiment of the present invention. The sum of the power of subframe nin TAG1 and the power of subframe n+1 in TAG2 may be more than themaximum allowed transmission power of the wireless device. In FIG. 14,power levels for subframes are shown to be fixed for simplicity. Duringthe transient period, for example at the two ends of each subframe,transmission power may change. For example, if a subframe duration is 1msec and a transient period duration is 20 micro-seconds, then thetransmit power may be substantially fixed during the subframe exceptduring the transient period where the power may change. In anotherexample embodiment, transient periods may also be defined at slotboundaries near or at the middle of a subframe.

FIG. 17 and FIG. 18 are illustrations of power limitations during timingoverlap periods between PUCCH and PUSCH transmissions or between twoPUSCH transmissions as per an aspect of an embodiment of the presentinvention. The overlap period may be in the range of, for example, onemicro-second to tens of micro-seconds. A rule may be defined forparallel transmission of PUCCH and PUSCH, or parallel transmission ofPUSCHs when the UE is in a power limited scenario. According to some ofthe various aspects of embodiments, PUCCH signal transmission power maybe assigned a higher power priority compared with PUSCH signaltransmission power. The discussion below focuses on UEs configured withmultiple TAGs.

If the PUCCH/PUSCH transmission of the wireless device on subframe n fora given serving cell in a TAG overlaps some period of the first symbolof the PUSCH transmission on subframe n+1 for a different serving cellin a different TAG, the UE may adjust its total transmission power tonot exceed the maximum allowable transmission power on any overlappingperiod. If the PUSCH transmission of the wireless device on subframe nfor a given serving cell in a TAG overlaps some period of the firstsymbol of the PUCCH transmission on subframe n+1 for a different servingcell in a different TAG, the wireless device may adjust its totaltransmission power to not exceed the maximum allowable transmissionpower on any overlapping period. This rule may be generalized coveringscenarios with multiple cell PUSCH transmissions and/or multiple cellPUSCH and/or PUCCH transmission overlaps.

If the transmission overlap between PUCCH and/or PUSCH(s) signals isbelow a second time period, during the overlap the power may be belowthe UE maximum allowed transmission power even if the sum of the PUCCHand/or PUSCH(s) subframe transmission powers may exceed the UE maximumallowed transmission power. During the transient period, the UE mayreduce its transmission power to a lower level compared with thetransmission power during the non-transient period of the subframe. Inthis case, even though PUCCH and/or PUSCH transmission power may exceedthe UE maximum allowed transmission power, the UE may not reduce PUSCHsubframe transmission power.

If the transmission overlap between PUCCH and/or PUSCH signals isrelatively large, then PUSCH subframe transmission power may be reducedif the sum of the PUCCH and PUSCH(s) subframe transmission powers exceedthe UE maximum allowed transmission power. In an example implementation,if the sum of the PUCCH and PUSCH(s) subframe transmission powers exceedthe UE maximum allowed transmission power and overlap between the PUCCHand/or PUSCH signals exceeds a first period, the PUSCH subframetransmission power may be reduced. In an example implementation, if sumof the PUSCH(s) subframe transmission power and the PUCCH subframetransmission power exceeds the UE maximum allowed transmission power andoverlap between the PUCCH and/or PUSCH(s) signals is below a secondperiod, the PUSCH may be transmitted without its subframe power beingreduced. The second period may be less than the transient period. The UEmay reduce transmission power of the PUCCH and/or PUSCH(s) signalsduring the transient period to overcome power limitations, and the UEmay not reduce (scale down) PUSCH subframe transmission power. Theprocess of using reduced power during transient periods to reduce PUSCHsubframe power reduction may increase spectral efficiency and reduce biterror rates. The UE may not restrict itself in calculating totaltransmission power by summing the PUSCH and/or PUCCH subframe power ofdifferent subframes regardless of the overlap period. The UE may takeadvantage of reduced power during a transient period to ensure the totalpower is below the maximum power during the overlapping period of timewhile the summation of the PUSCH and/or PUCCH subframe power may exceedthe power limit.

A UE receiver may cope with a relative propagation delay difference upto a certain limit (e.g. 30 μs) among the component carriers to beaggregated (e.g. in inter-band non-contiguous CA). The base station timealignment may be up to a certain limit, for example 1.3 μs. In theexample, a UE may cope with a delay spread of up to 31.3 μs among thecomponent carriers monitored at the receiver.

In examples presented in FIG. 17(a) and FIG. 17(b), a sum of thePUSCH/PUCCH subframe transmission power in subframe n and the PUSCHsubframe transmission power in subframe n+1 may exceed the maximumallowable transmission power. A PUSCH subframe transmission power may bereduced (scaled down) in FIG. 17(a). The UE may not be able to complywith power constraints when the overlap period is more than a firstperiod. For example, the overlap period in FIG. 17(a) may be 25micro-seconds or more. The UE may reduce a PUSCH subframe transmissionpower signal in FIG. 17(a). The UE may not transmit with reduced PUSCHsubframe transmission power FIG. 15(b). The UE may comply with powerrequirements by reducing the PUSCH/PUCCH transmission power during thetransient period (compared with the subframe transmission power). Thepartial overlap in FIG. 15(b) may be below a second period.

FIG. 18 provides a more detailed illustration of FIG. 17. In FIG. 18(a),the UE may reduce the PUSCH subframe transmission power. Without thePUSCH subframe power reduction, the UE may exceed its transmission powereven though it may reduce its power during the transient period. In FIG.18(b), the UE may transmit a PUCCH/PUSCH signal in subframe n in TAG1and a PUSCH signal in subframe n+1 in TAG2, even though the sum of thePUSCH subframe transmission power in subframe n+1 and the PUCCH/PUSCHsubframe transmission power in subframe n exceeds the UE total allowedtransmission power. The UE may comply with power requirements byreducing its power during the transient period. Other examples may beprovided with different power levels, overlap periods, more cells, moreTAGs, and/or the like.

To test an example operation as described in FIG. 17 and FIG. 18, a testset up may be implemented in which the TAG timing difference (oroverlapping period) is increased from a small period to a large period.The UE may be configured to transmit PUCCH signals on TAG1 and PUSCHsignals on TAG2. The UE may be put in a power limited condition (e.g. byincreasing the attenuation of the channel pathloss). As the TAG timingdifference increases, the probability of reducing the PUSCH subframetransmission power may also increase. For small TAG timing differences,the UE may comply with power requirements by reducing a transient periodpower. For a large TAG timing difference, a UE may reduce the PUSCHtransmission timing more often to comply with power requirements. Ingeneral, the channel priorities of the various signals may be consideredas PUCCH>PUSCH with UCI>PUSCH.

A similar process may be implemented to comply with power requirementswhen there is an overlapping PRACH signal transmission with PUSCH signaltransmission. If the UE is configured with multiple TAGs, the UE maytransmit PRACH signals in a secondary serving cell in parallel with thetransmission of PUSCH/PUCCH signals in a different serving cellbelonging to a different TAG. The UE may adjust the subframetransmission power of the PUSCH/PUCCH signals so that its totaltransmission power does not exceed the maximum allowable transmissionpower on the overlapped period. When the overlapping period is smallerthan a second period, the UE may comply with power requirements byreducing the transient period power of the PUSCH, PUCCH, and/or PRACHsignals and may not need to reduce subframe transmission power of thePUSCH and/or PUCCH signal transmissions.

According to some of the various embodiments, the L1 random accessprocedure may encompass the transmission of a random access preamble anda random access response. The remaining messages may be scheduled fortransmission by a higher layer on the shared data channel. A randomaccess channel may occupy six resource blocks in a subframe or set ofconsecutive subframes reserved for random access preamble transmissions.The eNodeB may not be prohibited from scheduling data in the resourceblocks reserved for random access channel preamble transmission.

The following steps may be required for the L1 random accessprocedure: 1) Layer 1 procedure may be triggered upon request of apreamble transmission by higher layers; 2) A preamble index, a targetpreamble received power (PREAMBLE_RECEIVED_TARGET_POWER), acorresponding RA-RNTI and a PRACH resource may be indicated by higherlayers as part of the request; 3) A preamble transmission power PPRACHmay be determined as PPRACH=min{P_(CMAX,c)(i),PREAMBLE_RECEIVED_TARGET_POWER+PL_(c)}[dBm], where P_(CMAX,c)(i) may bethe configured UE transmit power defined for subframe i of the primarycell and PL_(c) is the downlink pathloss estimate calculated in the UEfor the primary cell; 4) A preamble sequence may be selected from thepreamble sequence set using the preamble index; 5) A single preamble maybe transmitted using the selected preamble sequence with transmissionpower PPRACH on the indicated PRACH resource; 6) Detection of a PDCCHwith the indicated RA-RNTI may be attempted during a window controlledby higher layers. If detected, the corresponding DL-SCH transport blockmay be passed to higher layers. The higher layers may parse thetransport block and indicate a 20-bit uplink grant to the physicallayer.

The setting of the UE transmit power for a physical uplink sharedchannel (PUSCH) transmission in the absence of a physical random accesschannel transmission and a PUCCH transmission on the same cell may bedefined as follows. If the UE transmits the PUSCH signal without asimultaneous PUCCH signal for the serving cell c, then the UE maytransmit with power P_(PUSCH,c)(i) for PUSCH transmission in subframe ifor the serving cell c given by:

${P_{{PUSCH},\mspace{11mu} c}(i)} = {\min\left\{ \begin{matrix}{{P_{{CMAX},c}(i)},} \\{{10\mspace{11mu}{\log_{10}\left( {M_{{PUSCH},\mspace{11mu} c}(i)} \right)}} + {P_{{O_{-}{PUSCH}},\mspace{11mu} c}(j)} + {{\alpha_{c}(j)} \cdot {PL}_{c}} + {\Delta_{{TF},\; c}(i)} + {f_{c}(i)}}\end{matrix} \right\}}$

[dBm]

The setting of the UE Transmit power for a physical uplink sharedchannel (PUSCH) transmission in the presence of a physical random accesschannel transmission on an overlapping subframe in the same cell may bedefined as follows. The UE transmit power P_(PUSCH,c)(i) for the PUSCHtransmission in subframe i for the serving cell c may be given by:

${P_{{PUSCH},c}(i)} = {\min\left\{ \begin{matrix}{{10{\log_{10}\left( {{{\hat{P}}_{{CMAX},c}(i)} - {{\hat{P}}_{PRACH}(i)}} \right)}},} \\{{10\mspace{11mu}{\log_{10}\left( {M_{{PUSCH},c}(i)} \right)}} + {P_{{O_{-}{PUSCH}},c}(j)} + {{\alpha_{c}(j)} \cdot {PL}_{c}} + {\Delta_{{TF},c}(i)} + {f_{c}(i)}}\end{matrix} \right\}}$

[dBm]

The above formula may be applied when the amount of the power duringoverlap between transmissions of the random access preamble and thephysical uplink shared channel may not be adjusted by reducing the powerduring the transient period.

If the UE transmits a PUSCH signal simultaneously with PUCCH and PRACHsignals for the serving cell c, then the UE transmit powerP_(PUSCH,c)(i) for the PUSCH transmission in subframe i for the servingcell c may be given by:

${P_{{PUSCH},c}(i)} = {\min\left\{ \begin{matrix}{{10{\log_{10}\left( {{{\hat{P}}_{{CMAX},c}(i)} - {{\hat{P}}_{PUCCH}(i)} - {{\hat{P}}_{PRACH}(i)}} \right)}},} \\{{10\mspace{11mu}{\log_{10}\left( {M_{{PUSCH},c}(i)} \right)}} + {P_{{O_{-}{PUSCH}},c}(j)} + {{\alpha_{c}(j)} \cdot {PL}_{c}} + {\Delta_{{TF},c}(i)} + {f_{c}(i)}}\end{matrix} \right\}}$

[dBm]

If {circumflex over (P)}_(CMAX,c)(i)≤{circumflex over(P)}_(PUCCH)(i)−{circumflex over (P)}_(PRACH)(i), then PUSCH signal maybe dropped and may not be transmitted. PRACH transmission signal powerand PUCCH transmission signal power may have a higher priority comparedwith PUSCH transmission power.

In some other example embodiments, a UE may drop any scheduled SRS,PUSCH, and/or PUCCH signals when the UE is instructed to transmit arandom access preamble in parallel with SRS, PUSCH, and/or PUCCH signalsin the same cell group. The above power control rules may not apply to aUE that is not configured to transmit a PRACH in parallel with an SRS,PUCCH, and/or PUSCH signal in the same cell or in the same cell group.

A wireless device may receive at least one radio resource controlmessage from a base station. The at least one radio resource controlmessage may cause in the wireless device: configuration of a pluralityof cells comprising a primary cell and at least one secondary cell; andassignment of each of the at least one secondary cell to a cell group ina plurality of cell groups, each of the plurality of cell groupscomprising a subset of the plurality of cells. The wireless device mayreceive a control command causing the wireless device to transmit arandom access preamble on a random access channel of a first cell in afirst cell group in the plurality of cell groups. The wireless devicemay transmit overlapping in time with transmission of the random accesspreamble an uplink packet on a first subframe of the first cell.Transmission power of the uplink packet may be calculated considering: amaximum allowable transmission power in the first subframe of the firstcell; and transmission power of the random access preamble.

The calculation of transmission power of the uplink packet may comprisesubtracting a calculated power of the random access preamble from themaximum allowable transmission power in the first subframe of the firstcell if a summation of transmission powers of the uplink packet and therandom access preamble in the first subframe of the first cell exceedsthe maximum allowable transmission power. The maximum allowabletransmission power may be for the first cell. Each cell in the pluralityof cells may be assigned a maximum allowable transmission power. Theuplink packet may be one of the following: a physical uplink sharedchannel data packet; and a physical uplink control channel controlpacket. The at least one radio resource control message may causeconfiguration of the random access channel. The control command maycomprise an index of the random access preamble. In an exampleembodiment, the first cell group is a secondary cell group; and thefirst cell is a secondary cell in the secondary cell group.

Power control is an important aspect in wireless networks. Release 10 ofthe LTE technology standard provides power control mechanisms to controluplink transmission power of a wireless device employing many parametersincluding base station power control commands The wireless device maycalculate the transmission power for transmission of packets on eachactive carrier. The transmission power of each carrier may be calculatedaccording to many parameters and may be limited to a preconfiguredmaximum value. The wireless device may reduce the transmission powersbased on its total transmit power budget. Release 11 of the LTEtechnology standard may support configurations for multiple carriergroups. Each carrier group may have its own carrier timing. This mayintroduce various new challenges in controlling uplink transmissiontiming as well transmission power.

There may be a need for development of new processes for adjustinguplink timing of carriers in different carrier groups. There may also bea need for development of new processes for adjusting the uplinktransmission power in different carrier groups. Some of the powercontrol mechanisms in release 10 may not be applicable to an LTE radiointerface supporting multiple carrier group configurations. Whenmultiple TAGs are configured, random access processes may be defined forthe primary carrier as well as secondary carrier(s). Random accessprocesses may include random access preamble (RAP) transmissions andrandom access responses (RAR). Both RAP and RAR transmissions may impactpower control processes. Random access preamble transmissions may be ona primary or secondary carrier with random access resources. Randomaccess responses may be carried on the primary carrier. In LTE release10, random access responses may only be related to random accesspreambles transmitted on the primary carrier. When multiple TAGs areconfigured, there may be a need to re-examine random access processesand related impact on power control mechanisms. There may be a need forimprovements in power control mechanisms to integrate the power controlmechanisms with various types of random access transmissions in awireless network configured with multiple carrier groups.

FIG. 20 depicts a flow chart showing tasks in a wireless device as peran aspect of an embodiment of the present invention. According to someof the various aspects of embodiments, a wireless device may receivefrom a base station, at least one first control message. The at leastone first control message may include RRC control messages and mayconfigure an RRC connection. The at least one first control message maycause configuration of a plurality of cells comprising a primary celland at least one secondary cell at block 2002. Each of the plurality ofcells may comprise a downlink carrier and zero or one uplink carrier.The configuration may assign a cell to a cell group. A cell group indexmay identify one of a plurality of cell groups. The plurality of cellgroups may comprise a primary cell group and a secondary cell group. Theprimary cell group may comprise a first subset of the plurality ofcells. The first subset may comprise the primary cell. Uplinktransmissions by the wireless device in the primary cell group mayemploy a first synchronization signal transmitted on the primary cell asa primary timing reference. The secondary cell group may comprise asecond subset of the at least one secondary cell. The at least one firstcontrol message may further cause configuration of a plurality of randomaccess resource parameters. The random access resource parameters mayidentify random access resources for the primary cell and a firstsecondary cell in the secondary cell group. The at least one firstcontrol message may further cause configuration of power controlaccumulations for the first secondary cell.

The wireless device may receive a control command (PDCCH order) totransmit a random access preamble (RAP) on an uplink carrier at block2004. The wireless device may transmit a RAP in the uplink carrieridentified (implicitly or explicitly) by the control command at block2006. If the PDCCH order includes a carrier index, the RAP may betransmitted on the carrier identified by the carrier index. If the PDDCHorder does not include the carrier index, the RAP may be transmitted onthe same carrier as the carrier for the PDCCH order. The wireless devicemay receive a random access response (RAR) on the primary cell at block2008. The wireless device may decode and check the random accesspreamble identifier RAPID field in the RAR at 2010. If the wirelessdevice determines that the RAPID corresponds to a RAP transmitted by thewireless device at block 2012, the RAR and the uplink grant in the RARmay correspond to the uplink carrier in which the RAP was transmitted.The wireless device may reset power for the secondary carrier if theuplink grant is for the secondary carrier at 2014. The wireless devicemay reset power for the primary carrier if the uplink grant is for theprimary carrier at 2014.

FIG. 19 depicts an example of first parameter 1901 calculated over timeas per an aspect of an embodiment of the present invention. The wirelessdevice receives a first control packet providing a first uplink grant totransmit a first uplink packet in a first subframe 1916 of a firstsecondary cell. The wireless device may compute transmission power ofthe first uplink packet employing, at least in part, a first parametercalculated by accumulation of an initial value and at least one powercontrol value corresponding to a sequence of subframes 1914. Thesequence of subframes may start from an initial subframe 1912 and mayend with the first subframe 1916. The initial subframe 1912 may beidentified by the most recent subframe before the first subframe 1916with one of the following events 1910: a predefined transmit powerparameter value updated by higher layers; and a random access responsereceived corresponding to a transmitted random access preamble on thefirst secondary cell. 1903 illustrates an example of a positive powercontrol (command) value, 1905 shows illustrates an example of no powercontrol command (TPC value of zero), and 1907 illustrates an example ofa negative power control (command) value. The wireless device maytransmit the first uplink packet in radio resources identified by thefirst uplink grant.

FIG. 21 depicts a flow chart showing the tasks performed in a wirelessdevice as per an aspect of an embodiment of the present invention. Thewireless device may receive a RAR on the primary carrier at block 2102.The wireless device may not process the RAR or may not receive and/ordecode the RAR if the wireless device is not currently in a randomaccess process. The wireless device may check a RAPID field in the RARat block 2104. The wireless device may identify whether the RAPID fieldidentifies a RAP transmitted by the wireless device at block 2106. Ifthe RAPID field does not identify a RAP transmitted by the wirelessdevice, the wireless device may perform a normal power control processwithout resetting the power control process at block 2108. If the RAPIDfield identifies a RAP recently transmitted by the wireless device, thewireless device may decode the RAR. If the RAP was transmitted on theprimary carrier, the wireless device may reset the first parameter forthe primary carrier at 2114. If the RAP was transmitted on a secondarycarrier, the wireless device may reset the first parameter for thesecondary carrier at 2112.

The first control packet may comprise the first uplink grant and a firstpower control field. The first power control field may correspond to afirst power control value. The first power control field may correspondwith a pre-defined power control value, for example, according to apredefined table. Each subframe in the sequence of subframes may beassigned: the initial value; or one power control value in the at leastone power control value. The initial subframe may be assigned theinitial value. Other subframe(s) may be assigned a power control value(TPC value). If the sequence of subframes includes only one subframe,then the power of the one subframe may be set at the initial value.

A power control value in the at least one power control valuecorresponding to a subframe in the sequence of subframes may be zero ifone of the following conditions is satisfied: no power control isreceived for the subframe; the wireless device has reached a maximumpower in the subframe and the corresponding power control value ispositive; and the wireless device has reached a minimum power in thesubframe and the corresponding power control value is negative. A powercontrol value in the at least one power control value corresponding to asubframe in the sequence of subframes may be zero if one of thefollowing conditions is satisfied: the subframe is not an uplinksubframe in a TDD frame structure; the wireless device has reached amaximum power in the subframe and the corresponding power control valueis positive; and the wireless device has reached a minimum power in thesubframe and the corresponding power control value is negative.

The wireless device may receive the predefined transmit power parametervalue via a radio resource control protocol message. The initial valuemay be zero if the predefined transmit power parameter value is updatedin the initial subframe. The initial value may be the sum of a powercontrol value in the at least one power control value and an offsetvalue if the random access response is received. The wireless device mayreset the power control accumulation associated with a first uplinkcarrier of the first secondary cell if one of the events occurs. Theoffset value may correspond to a total power ramp-up from the first tothe last preamble transmitted by the wireless device during a randomaccess process corresponding to the random access response. The at leastone first control message may cause configuration of power controlaccumulations for the first secondary cell. The first control packet mayenable configuration of power control accumulations for the firstsecondary cell.

The first control packet may be received in PDCCH radio resources orEPDCCH radio resources. The first control packet may have a DCI format 0according to an LTE physical layer standard. A CRC of the first controlpacket may be scrambled by a temporary C-RNTI according to an LTEphysical layer standard. The first control packet may have one of thefollowing formats according to an LTE physical layer standard: a DCIformat 0; a DCI format 4; a DCI format 3; and a DCI format 3A. The firstuplink grant may identify radio resources employed for transmission ofthe first uplink packet on a first uplink carrier of the first secondarycell. The wireless device may receive the first power control field Ksubframes before the first subframe, wherein K is a preconfiguredinteger parameter greater than zero. The wireless device may receive thefirst control packet K subframes before the first subframe, wherein K isa preconfigured integer parameter greater than zero. K may be equal to 4for FDD frame structure.

The transmission power may be computed employing at least one of thefollowing parameters: bandwidth of radio resources identified by thefirst uplink grant; a downlink pathloss estimate; modulation and codingidentified by the first uplink grant; the first parameter; and/or thelike. The transmission power of the first uplink packet may be within apre-configured maximum power value. The wireless device may set thetransmission power to the pre-configured maximum power value if thetransmission power is above the pre-configured maximum power value. Thewireless device may selectively reduce the transmission power if thewireless device does not have enough power budget to transmit the firstuplink packet at the transmission power. The wireless device mayselectively reduce or modify the transmission power of the first uplinkpacket after computing the transmission power.

According to some of the various aspects of embodiments, the setting ofthe wireless device transmit power for a physical uplink shared channel(PUSCH) transmission may, for example, be defined as follows. If thewireless device transmits PUSCH without a simultaneous PUCCH for theserving cell c, then the wireless device transmit power P_(PUSCH,c)(i)for PUSCH transmission in subframe i for the serving cell c may be givenby

${P_{{PUSCH},c}(i)} = {\min\left\{ \begin{matrix}{{P_{{CMAX},c}(i)},} \\{{10\mspace{11mu}{\log_{10}\left( {M_{{PUSCH},c}(i)} \right)}} + {P_{{O_{-}{PUSCH}},c}(j)} + {{\alpha_{c}(j)} \cdot {PL}_{c}} + {\Delta_{{TF},c}(i)} + {f_{c}(i)}}\end{matrix} \right\}}$

[dBm]

If the wireless device transmits a PUSCH signal simultaneous with aPUCCH signal for the serving cell c, then the wireless device transmitpower P_(PUSCH,c)(i) for the PUSCH transmission in subframe i for theserving cell c may be given by:

${P_{{PUSCH},c}(i)} = {\min\left\{ \begin{matrix}{{10{\log_{10}\left( {{{\hat{P}}_{{CMAX},c}(i)} - {{\hat{P}}_{PUCCH}(i)}} \right)}},} \\{{10\mspace{11mu}{\log_{10}\left( {M_{{PUSCH},c}(i)} \right)}} + {P_{{O_{-}{PUSCH}},c}(j)} + {{\alpha_{c}(j)} \cdot {PL}_{c}} + {\Delta_{{TF},c}(i)} + {f_{c}(i)}}\end{matrix} \right\}}$

[dBm]

If the wireless device is not transmitting a PUSCH signal for theserving cell c, for the accumulation of a TPC (transmit power control)command received with DCI format 3/3A for PUSCH signal, the wirelessdevice may assume that the wireless device transmit power P_(PUSCH,c)(i)for the PUSCH transmission in subframe i for the serving cell c iscomputed by:

P _(PUSCH,c)(i)=min{P _(CMAX,c)(i), P _(O_PUSCH,c)(1)+α_(c)(1)·PL_(c) +f_(c)(i)}  [dBm]

where, P_(CMAX,c)(i) may be the configured wireless device transmitpower defined in subframe i for serving cell c and {circumflex over(P)}_(CMAX,c)(i) may be the linear value of P_(CMAX,c)(i). P_(CMAX,c)(i)may be defined according to the definitions in LTE standard release 10.{circumflex over (P)}_(PUCCH)(i) may be the linear value ofP_(PUCCH)(i). P_(PUCCH)(i) may be defined according to the definitionsin LTE standard release 10. M_(PUSCH,c)(i) may be the bandwidth of thePUSCH resource assignment expressed in number of resource blocks validfor subframe i and serving cell c. P_(O_PUSCH,c)(j) may be calculatedemploying parameters provided by higher layers. PL_(c) may be thedownlink pathloss estimate calculated in the wireless device for servingcell c in dB. Δ_(TF,c)(i) is calculated as a function of modulation andcoding.

δ_(PUSCH,c) may be a correction value, also referred to as a TPC commandand may be included in PDCCH/EPDCCH with DCI format 0/4 for serving cellc or jointly coded with other TPC commands in PDCCH with DCI format 3/3Awhose CRC parity bits may be scrambled with TPC-PUSCH-RNTI. The currentPUSCH power control adjustment state for serving cell c may be given byf_(c)(i) which may be predefined.

f_(c)(i)=f_(c)(i−1)+δ_(PUSCH,c)(i−K_(PUSCCH)) if accumulation is enabledbased on the parameter accumulation-enabled provided by higher layers orif the TPC command δ_(PUSCH,c) is included in a PDCCH/EPDCCH with DCIformat 0 for serving cell c, where δ_(PUSCH,c)(i−K_(PUSCH)) may besignaled on PDCCH/EPDCCH with DCI format 0/4 or PDCCH with DCI format3/3A on subframe i−K_(PUSCH), and where f_(c)(0) may be the first valueafter reset of accumulation. The value of K_(PUSCH) may be predefined.For serving cell c, the wireless device may attempt to decode aPDCCH/EPDCCH of DCI format 0/4 with the wireless device's CRNTI or DCIformat 0 for SPS C-RNTI and a PDCCH of DCI format 3/3A with thiswireless device's TPC-PUSCH-RNTI in every subframe except when in DRX orwhere serving cell c is deactivated. If DCI format 0/4 for serving cellc and DCI format 3/3A are both detected in the same subframe, then thewireless device may use the δ_(PUSCH,c) provided in DCI format 0/4.δ_(PUSCH,c)=0 dB for a subframe where no TPC command is decoded forserving cell c or where DRX occurs or i is not an uplink subframe inTDD. The δ_(PUSCH,c) dB accumulated values signaled on PDCCH/EPDCCH withDCI format 0/4 may be derived from a predefined table. If thePDCCH/EPDCCH with DCI format 0 is validated as a SPS activation orrelease PDCCH/EPDCCH, then δ_(PUSCH,c) is 0 dB. The δ_(PUSCH) dBaccumulated values signaled on PDCCH with DCI format 3/3A may be one ofSET1 derived from a predefined table or SET2 derived from a predefinedtable as determined by the parameter TPC-Index provided by higherlayers. If a wireless device has reached P_(CMAX,c)(i) for serving cellc, positive TPC commands for serving cell c may not be accumulated. Ifwireless device has reached minimum power, negative TPC commands may notbe accumulated.

f_(c)(i)=δ_(PUSCH,c)(i−K_(PUSCH)) if accumulation is not enabled forserving cell c based on the parameter Accumulation-enabled provided byhigher layers, where δ_(PUSCH,c)(i−K_(PUSCH)) may be signaled onPDCCH/EPDCCH with DCI format 0/4 for serving cell c on subframei−K_(PUSCH). The δ_(PUSCH,c) dB absolute values signaled on PDCCH/EPDCCHwith DCI format 0/4 may be derived from a predefined table. If thePDCCH/EPDCCH with DCI format 0 is validated as a SPS activation orrelease PDCCH, then δ_(PUSCH,c) is 0 dB. f_(c)(i)=f_(c)(i−1) for asubframe where no PDCCH/EPDCCH with DCI format 0/4 is decoded forserving cell c or where DRX occurs or i is not an uplink subframe inTDD.

For both types of f_(c)(*) (accumulation or current absolute) the firstvalue may be set as follows: If P_(O_UE_PUSCH,c) value is changed byhigher layers and serving cell c is the primary cell or, ifP_(O_UE_PUSCH,c) value is received by higher layers and serving cell cis a Secondary cell: f_(c)(0)=0; Else: If serving cell c is the servingcell the serving cell, in which the Random Access Preamble wastransmitted on the uplink carrier f_(c)(0)=ΔP_(rampup)+δ_(msg2), whereδ_(msg2) may be the TPC command indicated in the random access response,and ΔP_(rampup) may be provided by higher layers and may correspond tothe total power ramp-up from the first to the last preamble.

According to some of the various embodiments, a wireless device mayreceive at least one radio resource control message from a base station.The at least one radio resource control message may cause in thewireless device configuration of a plurality of cells comprising aprimary cell and at least one secondary cell. The at least one radioresource control message may further cause assignment of each of the atleast one secondary cell to a cell group in a plurality of cell groups.The plurality of cell groups may comprise a primary cell group and asecondary cell group. The primary cell group may comprise a first subsetof the plurality of cells. The first subset may comprise the primarycell. The secondary cell group may comprise a second subset of the atleast one secondary cell. The wireless device may receive a controlcommand to transmit a random access preamble on random access resourcesof a secondary cell in the secondary cell group.

The wireless device may transmit one or more times the random accesspreamble on the random access resources of the secondary cell. Thewireless device may receive a random access response providing an uplinkgrant to transmit an uplink packet. The wireless device may computetransmission power of the uplink packet employing, at least in part, afirst parameter calculated by summation of: a power control valuecorresponding to a power control field in the uplink grant; and a totalpower ramp-up from the first transmission to the last transmission ofthe random access preamble if the random access preamble is transmittedmore than one time. The wireless device may transmit the first uplinkpacket in radio resources identified by the first uplink grant.

The random access response may comprise a timing adjustment command Thewireless device may apply the timing adjustment command to the secondarycell group. The at least one radio resource control message may causeconfiguration of at least one power control parameter of the secondarycell. The uplink grant may comprise a radio resource allocationparameter; the power control field; and/or a modulation and codingindex. The transmission power may be computed employing at least one ofthe following parameters: bandwidth of radio resources identified by theuplink grant; a downlink pathloss estimate; modulation and codingidentified by the uplink grant; and the first parameter. The controlcommand comprises a preamble identifier of the random access preamble.The at least one radio resource control message may cause configurationof the random access resources on the secondary cell. The wirelessdevice may retransmits the random access preamble if the followingconditions are met: no random access response is received in response totransmission of the random access preamble within a period of time; anda maximum number of transmissions is not reached.

According to some of the various aspects of embodiments, the randomaccess procedure may be initiated by a PDCCH order or by the MACsublayer itself. Random access procedure on an SCell may be initiated bya PDCCH order. If a UE receives a PDCCH transmission consistent with aPDCCH order masked with its C-RNTI (radio network temporary identifier),and for a specific serving cell, the UE may initiate a random accessprocedure on this serving cell. For random access on the PCell a PDCCHorder or RRC optionally indicate the ra-PreambleIndex and thera-PRACH-MaskIndex; and for random access on an SCell, the PDCCH orderindicates the ra-PreambleIndex with a value different from zero and thera-PRACH-MaskIndex. For the pTAG preamble transmission on PRACH andreception of a PDCCH order may only be supported for PCell.

According to some of the various aspects of embodiments, the proceduremay use some of the following information: a) the available set of PRACHresources for the transmission of the random access preamble,prach-ConfigIndex, b) for PCell, the groups of random access preamblesand/or the set of available random access preambles in each group, c)for PCell, the preambles that are contained in random access preamblesgroup A and Random Access Preambles group B are calculated, d) the RAresponse window size ra-ResponseWindowSize, e) the power-ramping factorpowerRampingStep, f) the maximum number of preamble transmissionpreambleTransMax, g) the initial preamble powerpreambleInitialReceivedTargetPower, h) the preamble format based offsetDELTA_PREAMBLE, i) for PCell, the maximum number of Msg3 HARQtransmissions maxHARQ-Msg3Tx, j) for PCell, the Contention ResolutionTimer mac-ContentionResolutionTimer. These parameters may be updatedfrom upper layers before each Random Access procedure is initiated.

According to some of the various aspects of embodiments, the RandomAccess procedure may be performed as follows: Flush the Msg3 buffer; setthe PREAMBLE_TRANSMISSION_COUNTER to 1; set the backoff parameter valuein the UE to 0 msec; for the RN (relay node), suspend any RN subframeconfiguration; proceed to the selection of the Random Access Resource.There may be one Random Access procedure ongoing at any point in time.If the UE receives a request for a new Random Access procedure whileanother is already ongoing, it may be up to UE implementation whether tocontinue with the ongoing procedure or start with the new procedure.

According to some of the various aspects of embodiments, the RandomAccess Resource selection procedure may be performed as follows. Ifra-PreambleIndex (Random Access Preamble) and ra-PRACH-MaskIndex (PRACHMask Index) have been explicitly signalled and ra-PreambleIndex is notzero, then the Random Access Preamble and the PRACH Mask Index may bethose explicitly signalled. Otherwise, the Random Access Preamble may beselected by the UE.

The UE may determine the next available subframe containing PRACHpermitted by the restrictions given by the prach-ConfigIndex, the PRACHMask Index and physical layer timing requirements (a UE may take intoaccount the possible occurrence of measurement gaps when determining thenext available PRACH subframe). If the transmission mode is TDD and thePRACH Mask Index is equal to zero, then if ra-PreambleIndex wasexplicitly signalled and it was not 0 (i.e., not selected by MAC), thenrandomly select, with equal probability, one PRACH from the PRACHsavailable in the determined subframe. Else, the UE may randomly select,with equal probability, one PRACH from the PRACHs available in thedetermined subframe and the next two consecutive subframes. If thetransmission mode is not TDD or the PRACH Mask Index is not equal tozero, a UE may determine a PRACH within the determined subframe inaccordance with the requirements of the PRACH Mask Index. Then the UEmay proceed to the transmission of the Random Access Preamble.

PRACH mask index values may range for example from 0 to 16. PRACH maskindex value may determine the allowed PRACH resource index that may beused for transmission. For example, PRACH mask index 0 may mean that allPRACH resource indexes are allowed; or PRACH mask index 1 may mean thatPRACH resource index 0 may be used. PRACH mask index may have differentmeaning in TDD and FDD systems.

The random-access procedure may be performed by UE settingPREAMBLE_RECEIVED_TARGET_POWER topreambleInitialReceivedTargetPower+DELTA_PREAMBLE+(PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep.The UE may instruct the physical layer to transmit a preamble using theselected PRACH, corresponding RA-RNTI, preamble index andPREAMBLE_RECEIVED_TARGET_POWER.

According to some of the various aspects of embodiments, once the randomaccess preamble is transmitted and regardless of the possible occurrenceof a measurement gap, the UE may monitor the PDCCH of the PCell forrandom access response(s) identified by the RA-RNTI (random access radionetwork identifier) a specific RA-RNTI defined below, in the randomaccess response (RAR) window which may start at the subframe thatcontains the end of the preamble transmission plus three subframes andhas length ra-ResponseWindowSize subframes. The specific RA-RNTIassociated with the PRACH in which the Random Access Preamble istransmitted, is computed as: RA-RNTI=1+t_id+10*f_id. Where t_id may bethe index of the first subframe of the specified PRACH (0≤t_id<10), andf_id is the index of the specified PRACH within that subframe, inascending order of frequency domain (0≤f_id<6). The UE may stopmonitoring for RAR(s) after successful reception of a RAR containingrandom access preamble identifiers that matches the transmitted randomaccess preamble.

According to some of the various aspects of embodiments, if a downlinkassignment for this TTI (transmission time interval) has been receivedon the PDCCH for the RA-RNTI and the received TB (transport block) issuccessfully decoded, the UE may regardless of the possible occurrenceof a measurement gap: if the RAR contains a backoff indicator (BI)subheader, set the backoff parameter value in the UE employing the BIfield of the backoff indicator subheader, else, set the backoffparameter value in the UE to zero msec. If the RAR contains a randomaccess preamble identifier corresponding to the transmitted randomaccess preamble, the UE may consider this RAR reception successful andapply the following actions for the serving cell where the random accesspreamble was transmitted: process the received riming advance commandfor the cell group in which the preamble was transmitted, indicate thepreambleInitialReceivedTargetPower and the amount of power rampingapplied to the latest preamble transmission to lower layers (i.e.,(PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep); process thereceived uplink grant value and indicate it to the lower layers; theuplink grant is applicable to uplink of the cell in which the preamblewas transmitted. If ra-PreambleIndex was explicitly signalled and it wasnot zero (e.g., not selected by MAC), consider the random accessprocedure successfully completed. Otherwise, if the Random AccessPreamble was selected by UE MAC, set the Temporary C-RNTI to the valuereceived in the RAR message. When an uplink transmission is required,e.g., for contention resolution, the eNB may not provide a grant smallerthan 56 bits in the Random Access Response.

According to some of the various aspects of embodiments, if no RAR isreceived within the RAR window, or if none of all received RAR containsa random access preamble identifier corresponding to the transmittedrandom access preamble, the random access response reception mayconsidered not successful. If RAR is not received, UE may incrementPREAMBLE_TRANSMISSION_COUNTER by 1. IfPREAMBLE_TRANSMISSION_COUNTER=preambleTransMax+1 and random accesspreamble is transmitted on the PCell, then UE may indicate a randomaccess problem to upper layers (RRC). This may result in radio linkfailure. If PREAMBLE_TRANSMISSION_COUNTER=preambleTransMax+1 and therandom access preamble is transmitted on an SCell, then UE may considerthe random access procedure unsuccessfully completed. UE may stay in RRCconnected mode and keep the RRC connection active even though a randomaccess procedure unsuccessfully completed on a secondary TAG. Accordingto some of the various aspects of embodiments, at completion of therandom access procedure, the UE may discard explicitly signalledra-PreambleIndex and ra-PRACH-MaskIndex, if any; and flush the HARQbuffer used for transmission of the MAC PDU in the Msg3 buffer. Inaddition, the RN may resume the suspended RN subframe configuration, ifany.

According to some of the various aspects of embodiments, a UE may have aconfigurable timer timeAlignmentTimer per TAG. The timeAlignmentTimer isused to control how long the UE considers the Serving Cells belonging tothe associated TAG to be uplink time aligned (in-sync). When a TimingAdvance Command MAC control element is received, the UE may apply theriming advance command for the indicated TAG, and start or restart thetimeAlignmentTimer associated with the indicated TAG. When a timingadvance command is received in a RAR message for a serving cellbelonging to a TAG and if the random access preamble was not selected byUE MAC, the UE may apply the timing advance command for this TAG, andmay start or restart the timeAlignmentTimer associated with this TAG.When a timeAlignmentTimer associated with the pTAG expires, the UE may:flush all HARQ buffers for all serving cells; notify RRC to releasePUCCH/SRS for all serving cells; clear any configured downlinkassignments and uplink grants; and consider all runningtimeAlignmentTimers as expired. When a timeAlignmentTimer associatedwith an sTAG expires, then for all Serving Cells belonging to this TAG,the UE may flush all HARQ buffers; and notify RRC to release SRS. The UEmay not perform any uplink transmission on a serving Cell except therandom access preamble transmission when the timeAlignmentTimerassociated with the TAG to which this serving cell belongs is notrunning When the timeAlignmentTimer associated with the pTAG is notrunning, the UE may not perform any uplink transmission on any servingcell except the random access preamble transmission on the PCell. A UEstores or maintains N_(TA) (current timing advance value of an sTAG)upon expiry of associated timeAlignmentTimer. The UE may apply areceived timing advance command MAC control element and startsassociated timeAlignmentTimer. Transmission of the uplink radio framenumber i from the UE may start (N_(TA)+N_(TA offset))×T_(s) secondsbefore the start of the corresponding downlink radio frame at the UE,where 0≤N_(TA)≤20512. In an example implementation, N_(TA offset)=0 forframe structure type 1 (FDD) and N_(TA offset)=624 for frame structuretype 2 (TDD).

According to some of the various aspects of embodiments, upon receptionof a timing advance command for a TAG containing the primary cell, theUE may adjust uplink transmission timing for PUCCH/PUSCH/SRS of theprimary cell based on the received timing advance command The ULtransmission timing for PUSCH/SRS of a secondary cell may be the same asthe primary cell if the secondary cell and the primary cell belong tothe same TAG. Upon reception of a timing advance command for a TAG notcontaining the primary cell, the UE may adjust uplink transmissiontiming for PUSCH/SRS of secondary cells in the TAG based on the receivedtiming advance command where the UL transmission timing for PUSCH/SRS isthe same for all the secondary cells in the TAG.

The timing advance command for a TAG may indicate the change of theuplink timing relative to the current uplink timing for the TAG asmultiples of 16T_(s) (T_(s): sampling time unit). The start timing ofthe random access preamble may obtained employing a downlinksynchronization time in the same TAG. In case of random access response,an 11-bit timing advance command, TA, for a TAG may indicate N_(TA)values by index values of TA=0, 1, 2, . . . , 1282, where an amount ofthe time alignment for the TAG may be given by N_(TA)=TA×16. In othercases, a 6-bit timing advance command, TA, for a TAG may indicateadjustment of the current N_(TA) value, N_(TA,old), to the new N_(TA)value, N_(TA,new), by index values of TA=0, 1, 2, . . . , 63, whereN_(TA,new)=N_(TA,old)+(TA−31)×16. Here, adjustment of N_(TA) value by apositive or a negative amount indicates advancing or delaying the uplinktransmission timing for the TAG by a given amount respectively. For atiming advance command received on subframe n, the correspondingadjustment of the uplink transmission timing may apply from thebeginning of subframe n+6. For serving cells in the same TAG, when theUE's uplink PUCCH/PUSCH/SRS transmissions in subframe n and subframe n+1are overlapped due to the timing adjustment, the UE may completetransmission of subframe n and not transmit the overlapped part ofsubframe n+1. If the received downlink timing changes and is notcompensated or is only partly compensated by the uplink timingadjustment without timing advance command, the UE may change N_(TA)accordingly.

Downlink frames and subframes of downlink carriers may be time aligned(by the base station) in carrier aggregation and multiple TAGconfiguration. Time alignment errors may be tolerated to some extent.For example, for intra-band contiguous carrier aggregation, timealignment error may not exceed 130 ns. In another example, forintra-band non-contiguous carrier aggregation, time alignment error maynot exceed 260 ns. In another example, for inter-band carrieraggregation, time alignment error may not exceed 1.3 μs.

The UE may have capability to follow the frame timing change of theconnected base station. The uplink frame transmission may take place(N_(TA)+N_(TA offset))×T_(s) before the reception of the first detectedpath (in time) of the corresponding downlink frame from the referencecell. The UE may be configured with a pTAG containing the PCell. ThepTAG may also contain one or more SCells, if configured. The UE may alsobe configured with one or more sTAGs, in which case the pTAG may containone PCell and the sTAG may contain at least one SCell with configureduplink In pTAG, UE may use the PCell as the reference cell for derivingthe UE transmit timing for cells in the pTAG. The UE may employ asynchronization signal on the reference cell to drive downlink timing.When a UE is configured with an sTAG, the UE may use an activated SCellfrom the sTAG for deriving the UE transmit timing for cell in the sTAG.

In at least one of the various embodiments, uplink physical channel(s)may correspond to a set of resource elements carrying informationoriginating from higher layers. The following example uplink physicalchannel(s) may be defined for uplink: a) Physical Uplink Shared Channel(PUSCH), b) Physical Uplink Control Channel (PUCCH), c) Physical RandomAccess Channel (PRACH), and/or the like. Uplink physical signal(s) maybe used by the physical layer and may not carry information originatingfrom higher layers. For example, reference signal(s) may be consideredas uplink physical signal(s). Transmitted signal(s) in slot(s) may bedescribed by one or several resource grids including, for example,subcarriers and SC-FDMA or OFDMA symbols. Antenna port(s) may be definedsuch that the channel over which symbol(s) on antenna port(s) may beconveyed and/or inferred from the channel over which other symbol(s) onthe same antenna port(s) is/are conveyed. There may be one resource gridper antenna port. The antenna port(s) used for transmission of physicalchannel(s) or signal(s) may depend on the number of antenna port(s)configured for the physical channel(s) or signal(s).

According to some of the various embodiments, physical downlink controlchannel(s) may carry transport format, scheduling assignments, uplinkpower control, and other control information. PDCCH may support multipleformats. Multiple PDCCH packets may be transmitted in a subframe.According to some of the various embodiments, scheduling controlpacket(s) may be transmitted for packet(s) or group(s) of packetstransmitted in downlink shared channel(s). Scheduling control packet(s)may include information about subcarriers used for packettransmission(s). PDCCH may also provide power control commands foruplink channels. PDCCH channel(s) may carry a plurality of downlinkcontrol packets in subframe(s). Enhance PDCCH may be implemented in acell as an option to carrier control information. According to some ofthe various embodiments, PHICH may carry the hybrid-ARQ (automaticrepeat request) ACK/NACK.

Other arrangements for PCFICH, PHICH, PDCCH, enhanced PDCCH, and/orPDSCH may be supported. The configurations presented here are forexample purposes. In another example, resources PCFICH, PHICH, and/orPDCCH radio resources may be transmitted in radio resources including asubset of subcarriers and pre-defined time duration in each or some ofthe subframes. In an example, PUSCH resource(s) may start from the firstsymbol. In another example embodiment, radio resource configuration(s)for PUSCH, PUCCH, and/or PRACH (physical random access channel) may usea different configuration. For example, channels may be timemultiplexed, or time/frequency multiplexed when mapped to uplink radioresources.

According to some of the various aspects of embodiments, the physicallayer random access preamble may comprise a cyclic prefix of length Tcpand a sequence part of length Tseq. The parameter values may bepre-defined and depend on the frame structure and a random accessconfiguration. In an example embodiment, Tcp may be 0.1 msec, and Tseqmay be 0.9 msec. Higher layers may control the preamble format. Thetransmission of a random access preamble, if triggered by the MAC layer,may be restricted to certain time and frequency resources. The start ofa random access preamble may be aligned with the start of thecorresponding uplink subframe at a wireless device with N_(TA)=0.

According to an example embodiment, random access preambles may begenerated from Zadoff-Chu sequences with a zero correlation zone,generated from one or several root Zadoff-Chu sequences. In anotherexample embodiment, the preambles may also be generated using otherrandom sequences such as Gold sequences. The network may configure theset of preamble sequences a wireless device may be allowed to use.According to some of the various aspects of embodiments, there may be amultitude of preambles (e.g. 64) available in cell(s). From the physicallayer perspective, the physical layer random access procedure mayinclude the transmission of random access preamble(s) and random accessresponse(s). Remaining message(s) may be scheduled for transmission by ahigher layer on the shared data channel and may not be considered partof the physical layer random access procedure. For example, a randomaccess channel may occupy 6 resource blocks in a subframe or set ofconsecutive subframes reserved for random access preamble transmissions.

According to some of the various embodiments, the following actions maybe followed for a physical random access procedure: 1) layer 1 proceduremay be triggered upon request of a preamble transmission by higherlayers; 2) a preamble index, a target preamble received power, acorresponding RA-RNTI (random access-radio network temporary identifier)and/or a PRACH resource may be indicated by higher layers as part of arequest; 3) a preamble transmission power P_PRACH may be determined; 4)a preamble sequence may be selected from the preamble sequence set usingthe preamble index; 5) a single preamble may be transmitted usingselected preamble sequence(s) with transmission power P_PRACH on theindicated PRACH resource; 6) detection of a PDCCH with the indicated RARmay be attempted during a window controlled by higher layers; and/or thelike. If detected, the corresponding downlink shared channel transportblock may be passed to higher layers. The higher layers may parsetransport block(s) and/or indicate an uplink grant to the physicallayer(s).

Before a wireless device initiates transmission of a random accesspreamble, it may access one or many of the following types ofinformation: a) available set(s) of PRACH resources for the transmissionof a random access preamble; b) group(s) of random access preambles andset(s) of available random access preambles in group(s); c) randomaccess response window size(s); d) power-ramping factor(s); e) maximumnumber(s) of preamble transmission(s); f) initial preamble power; g)preamble format based offset(s); h) contention resolution timer(s);and/or the like. These parameters may be updated from upper layers ormay be received from the base station before random access procedure(s)may be initiated.

According to some of the various aspects of embodiments, a wirelessdevice may select a random access preamble using available information.The preamble may be signaled by a base station or the preamble may berandomly selected by the wireless device. The wireless device maydetermine the next available subframe containing PRACH permitted byrestrictions given by the base station and the physical layer timingrequirements for TDD or FDD. Subframe timing and the timing oftransmitting the random access preamble may be determined based, atleast in part, on synchronization signals received from the base stationand/or the information received from the base station. The wirelessdevice may proceed to the transmission of the random access preamblewhen it has determined the timing. The random access preamble may betransmitted on a second plurality of subcarriers on the first uplinkcarrier.

According to some of the various aspects of embodiments, once a randomaccess preamble is transmitted, a wireless device may monitor the PDCCHof a primary carrier for random access response(s), in a random accessresponse window. There may be a pre-known identifier in PDCCH thatidentifies a random access response. The wireless device may stopmonitoring for random access response(s) after successful reception of arandom access response containing random access preamble identifiersthat matches the transmitted random access preamble and/or a randomaccess response address to a wireless device identifier. A base stationrandom access response may include a time alignment command. Thewireless device may process the received time alignment command and mayadjust its uplink transmission timing according the time alignment valuein the command. For example, in a random access response, a timealignment command may be coded using 11 bits, where an amount of thetime alignment may be based on the value in the command In an exampleembodiment, when an uplink transmission is required, the base stationmay provide the wireless device a grant for uplink transmission.

If no random access response is received within the random accessresponse window, and/or if none of the received random access responsescontains a random access preamble identifier corresponding to thetransmitted random access preamble, the random access response receptionmay be considered unsuccessful and the wireless device may, based on thebackoff parameter in the wireless device, select a random backoff timeand delay the subsequent random access transmission by the backoff time,and may retransmit another random access preamble.

According to some of the various aspects of embodiments, a wirelessdevice may transmit packets on an uplink carrier. Uplink packettransmission timing may be calculated in the wireless device using thetiming of synchronization signal(s) received in a downlink. Uponreception of a timing alignment command by the wireless device, thewireless device may adjust its uplink transmission timing. The timingalignment command may indicate the change of the uplink timing relativeto the current uplink timing. The uplink transmission timing for anuplink carrier may be determined using time alignment commands and/ordownlink reference signals.

According to some of the various aspects of embodiments, a timealignment command may indicate timing adjustment for transmission ofsignals on uplink carriers. For example, a time alignment command mayuse 6 bits. Adjustment of the uplink timing by a positive or a negativeamount indicates advancing or delaying the uplink transmission timing bya given amount respectively.

For a timing alignment command received on subframe n, the correspondingadjustment of the timing may be applied with some delay, for example, itmay be applied from the beginning of subframe n+6. When the wirelessdevice's uplink transmissions in subframe n and subframe n+1 areoverlapped due to the timing adjustment, the wireless device maytransmit complete subframe n and may not transmit the overlapped part ofsubframe n+1.

According to some of the various aspects of embodiments, a wirelessdevice may be preconfigured with one or more carriers. When the wirelessdevice is configured with more than one carrier, the base station and/orwireless device may activate and/or deactivate the configured carriers.One of the carriers (the primary carrier) may always be activated. Othercarriers may be deactivated by default and/or may be activated by a basestation when needed. A base station may activate and deactivate carriersby sending an activation/deactivation MAC control element. Furthermore,the UE may maintain a carrier deactivation timer per configured carrierand deactivate the associated carrier upon its expiry. The same initialtimer value may apply to instance(s) of the carrier deactivation timer.The initial value of the timer may be configured by a network. Theconfigured carriers (unless the primary carrier) may be initiallydeactivated upon addition and after a handover.

According to some of the various aspects of embodiments, if a wirelessdevice receives an activation/deactivation MAC control elementactivating the carrier, the wireless device may activate the carrier,and/or may apply normal carrier operation including: sounding referencesignal transmissions on the carrier (if the carrier is uplink timealigned), CQI (channel quality indicator)/PMI (precoding matrixindicator)/RI (ranking indicator) reporting for the carrier, PDCCHmonitoring on the carrier, PDCCH monitoring for the carrier, start orrestart the carrier deactivation timer associated with the carrier,and/or the like. If the device receives an activation/deactivation MACcontrol element deactivating the carrier, and/or if the carrierdeactivation timer associated with the activated carrier expires, thebase station or device may deactivate the carrier, and may stop thecarrier deactivation timer associated with the carrier, and/or may flushHARQ buffers associated with the carrier.

If PDCCH on a carrier scheduling the activated carrier indicates anuplink grant or a downlink assignment for the activated carrier, thedevice may restart the carrier deactivation timer associated with thecarrier. When a carrier is deactivated, the wireless device may nottransmit SRS (sounding reference signal) for the carrier, may not reportCQI/PMI/RI for the carrier, may not transmit on UL-SCH for the carrier,may not monitor the PDCCH on the carrier, and/or may not monitor thePDCCH for the carrier.

In this specification, “a” and “an” and similar phrases are to beinterpreted as “at least one” and “one or more.” In this specification,the term “may” is to be interpreted as “may, for example,” In otherwords, the term “may” is indicative that the phrase following the term“may” is an example of one of a multitude of suitable possibilities thatmay, or may not, be employed to one or more of the various embodiments.If A and B are sets and every element of A is also an element of B, A iscalled a subset of B. In this specification, only non-empty sets andsubsets are considered. For example, possible subsets of B={cell1,cell2} are: {cell1}, {cell2}, and {cell1, cell2}.

In this specification, parameters (Information elements: IEs) maycomprise one or more objects, and each of those objects may comprise oneor more other objects. For example, if parameter (IE) N comprisesparameter (IE) M, and parameter (IE) M comprises parameter (IE) K, andparameter (IE) K comprises parameter (information element) J, then, forexample, N comprises K, and N comprises J.

Many of the elements described in the disclosed embodiments may beimplemented as modules. A module is defined here as an isolatableelement that performs a defined function and has a defined interface toother elements. The modules described in this disclosure may beimplemented in hardware, software in combination with hardware,firmware, wetware (i.e hardware with a biological element) or acombination thereof, all of which are behaviorally equivalent. Forexample, modules may be implemented as a software routine written in acomputer language configured to be executed by a hardware machine (suchas C, C++, Fortran, Java, Basic, Matlab or the like) or amodeling/simulation program such as Simulink, Stateflow, GNU Octave, orLabVIEWMathScript. Additionally, it may be possible to implement modulesusing physical hardware that incorporates discrete or programmableanalog, digital and/or quantum hardware. Examples of programmablehardware comprise: computers, microcontrollers, microprocessors,application-specific integrated circuits (ASICs); field programmablegate arrays (FPGAs); and complex programmable logic devices (CPLDs).Computers, microcontrollers and microprocessors are programmed usinglanguages such as assembly, C, C++ or the like. FPGAs, ASICs and CPLDsare often programmed using hardware description languages (HDL) such asVHSIC hardware description language (VHDL) or Verilog that configureconnections between internal hardware modules with lesser functionalityon a programmable device. Finally, it needs to be emphasized that theabove mentioned technologies are often used in combination to achievethe result of a functional module.

The disclosure of this patent document incorporates material which issubject to copyright protection. The copyright owner has no objection tothe facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the Patent and Trademark Officepatent file or records, for the limited purposes required by law, butotherwise reserves all copyright rights whatsoever.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example, and notlimitation. It will be apparent to persons skilled in the relevantart(s) that various changes in form and detail can be made thereinwithout departing from the spirit and scope. In fact, after reading theabove description, it will be apparent to one skilled in the relevantart(s) how to implement alternative embodiments. Thus, the presentembodiments should not be limited by any of the above describedexemplary embodiments. In particular, it should be noted that, forexample purposes, the above explanation has focused on the example(s)using FDD communication systems. However, one skilled in the art willrecognize that embodiments of the invention may also be implemented inTDD communication systems. The disclosed methods and systems may beimplemented in wireless or wireline systems. The features of variousembodiments presented in this invention may be combined. One or manyfeatures (method or system) of one embodiment may be implemented inother embodiments. Only a limited number of example combinations areshown to indicate to one skilled in the art the possibility of featuresthat may be combined in various embodiments to create enhancedtransmission and reception systems and methods.

In addition, it should be understood that any figures which highlightthe functionality and advantages, are presented for example purposesonly. The disclosed architecture is sufficiently flexible andconfigurable, such that it may be utilized in ways other than thatshown. For example, the actions listed in any flowchart may bere-ordered or only optionally used in some embodiments.

Further, the purpose of the Abstract of the Disclosure is to enable theU.S. Patent and Trademark Office and the public generally, andespecially the scientists, engineers and practitioners in the art whoare not familiar with patent or legal terms or phraseology, to determinequickly from a cursory inspection the nature and essence of thetechnical disclosure of the application. The Abstract of the Disclosureis not intended to be limiting as to the scope in any way.

Finally, it is the applicant's intent that only claims that include theexpress language “means for” or “step for” be interpreted under 35U.S.C. 112, paragraph 6. Claims that do not expressly include the phrase“means for” or “step for” are not to be interpreted under 35 U.S.C. 112,paragraph 6.

1. A method comprising: transmitting, by a wireless device via aplurality of symbols of a time interval and via a first cell of a cellgroup, a packet, wherein: the plurality of symbols of the time intervalcomprises a last symbol of the time interval; and a scheduledtransmission of a sounding reference signal (SRS), in the last symbol ofthe time interval, overlaps in time with the packet, wherein thescheduled transmission of the SRS is via a second cell of the cellgroup; and based on determining that the wireless device is configuredfor more than one cell group, transmitting the SRS.
 2. The method ofclaim 1, further comprising: receiving, by the wireless device, at leastone message comprising configuration parameters of: a plurality of cellscomprising the first cell and the second cell; and the SRS.
 3. Themethod of claim 1, wherein the wireless device has sufficient power totransmit the SRS overlapping in time with the packet.
 4. The method ofclaim 1, wherein the transmitting the SRS is further based on adetermination that a random access preamble is not configured fortransmissions in one or more symbols comprising the last symbol of thetime interval.
 5. The method of claim 1, wherein the transmitting theSRS comprises transmitting the SRS after one or more of: receiving aphysical downlink control channel packet; or receiving a radio resourcecontrol message.
 6. The method of claim 1, further comprisingprioritizing the transmitting the SRS lower than: a transmission of arandom access preamble; and the transmitting the packet.
 7. The methodof claim 1, wherein the packet comprises a physical uplink controlchannel packet.
 8. The method of claim 1, wherein the packet comprises aphysical uplink shared channel packet.
 9. The method of claim 1, whereinthe scheduled transmission of the SRS partially overlaps with thepacket.
 10. The method of claim 1, wherein the scheduled transmission ofthe SRS fully overlaps with the packet.
 11. A method comprising:transmitting, by a wireless device, a packet via a plurality of symbolsof a time interval and via a first cell of a cell group, wherein: theplurality of symbols of the time interval comprises a last symbol of thetime interval; and a scheduled transmission of a sounding referencesignal (SRS), in the last symbol of the time interval, overlaps in timewith the packet, wherein the scheduled transmission of the SRS is via asecond cell of the cell group; and based on determining that thewireless device is not configured for more than one cell group, droppingthe scheduled transmission of the SRS.
 12. The method of claim 11,further comprising: receiving, by the wireless device, at least onemessage comprising configuration parameters of: a plurality of cellscomprising the first cell and the second cell; and the SRS.
 13. Themethod of claim 11, wherein the wireless device has sufficient power totransmit the SRS overlapping in time with the packet.
 14. The method ofclaim 11, wherein the dropping the scheduled transmission of the SRS isfurther based on a determination that a random access preamble isconfigured for transmissions in one or more symbols comprising the lastsymbol of the time interval.
 15. The method of claim 11, wherein thescheduled transmission of the SRS comprises a scheduled transmission ofthe SRS after one or more of: receiving a physical downlink controlchannel packet; or receiving a radio resource control message.
 16. Themethod of claim 11, wherein the packet comprises a physical uplinkcontrol channel packet.
 17. The method of claim 11, wherein the packetcomprises a physical uplink shared channel packet.
 18. The method ofclaim 11, wherein the scheduled transmission of the SRS partiallyoverlaps with the packet.
 19. The method of claim 11, wherein thescheduled transmission of the SRS fully overlaps with the packet.
 20. Awireless device comprising: one or more processors; and memory storinginstructions that, when executed by the one or more processors,configure the wireless device to: transmit, via a plurality of symbolsof a time interval and via a first cell of a cell group, a packet,wherein: the plurality of symbols of the time interval comprises a lastsymbol of the time interval; and a scheduled transmission of a soundingreference signal (SRS), in the last symbol of the time interval,overlaps in time with the packet, wherein the scheduled transmission ofthe SRS is via a second cell of the cell group; and based on determiningthat the wireless device is configured for more than one cell group,transmit the SRS.
 21. The wireless device of claim 20, wherein theinstructions, when executed by the one or more processors, furtherconfigure the wireless device to receive at least one message comprisingconfiguration parameters of: a plurality of cells comprising the firstcell and the second cell; and the SRS.
 22. The wireless device of claim20, wherein the wireless device has sufficient power to transmit the SRSoverlapping in time with the packet.
 23. The wireless device of claim20, wherein the instructions, when executed by the one or moreprocessors, configure the wireless device to transmit the SRS furtherbased on a determination that a random access preamble is not configuredfor transmissions in one or more symbols comprising the last symbol ofthe time interval.
 24. The wireless device of claim 20, wherein theinstructions, when executed by the one or more processors, configure thewireless device to transmit the SRS after one or more of: receiving aphysical downlink control channel packet; or receiving a radio resourcecontrol message.
 25. The wireless device of claim 20, wherein theinstructions, when executed by the one or more processors, furtherconfigure the wireless device to prioritize transmitting the SRS lowerthan: a transmission of a random access preamble; and a transmission ofthe packet.
 26. The wireless device of claim 20, wherein the packetcomprises a physical uplink control channel packet.
 27. The wirelessdevice of claim 20, wherein the packet comprises a physical uplinkshared channel packet.
 28. A wireless device comprising: one or moreprocessors; and memory storing instructions that, when executed by theone or more processors, configure the wireless device to: transmit, apacket via a plurality of symbols of a time interval and via a firstcell of a cell group, wherein: the plurality of symbols of the timeinterval comprises a last symbol of the time interval; and a scheduledtransmission of a sounding reference signal (SRS), in the last symbol ofthe time interval, overlaps in time with the packet, wherein thescheduled transmission of the SRS is via a second cell of the cellgroup; and based on determining that the wireless device is notconfigured for more than one cell group, drop the scheduled transmissionof the SRS.
 29. The wireless device of claim 28, wherein theinstructions, when executed by the one or more processors, furtherconfigure the wireless device to receive at least one message comprisingconfiguration parameters of: a plurality of cells comprising the firstcell and the second cell; and the SRS.
 30. The wireless device of claim28, wherein the wireless device has sufficient power to transmit the SRSoverlapping in time with the packet.
 31. The wireless device of claim28, wherein the instructions, when executed by the one or moreprocessors, configure the wireless device to drop the SRS further basedon a determination that a random access preamble is configured fortransmissions in one or more symbols comprising the last symbol of thetime interval.
 32. The wireless device of claim 28, wherein thescheduled transmission of the SRS comprises a scheduled transmission ofthe SRS after one or more of: receiving a physical downlink controlchannel packet; or receiving a radio resource control message.
 33. Thewireless device of claim 28, wherein the packet comprises a physicaluplink control channel packet.
 34. The wireless device of claim 28,wherein the packet comprises a physical uplink shared channel packet.